diff --git a/components/ScannedCardItem.js b/components/ScannedCardItem.js
index ba76275..292ee66 100644
--- a/components/ScannedCardItem.js
+++ b/components/ScannedCardItem.js
@@ -15,6 +15,7 @@ export default function ScannedCardItem({
   onAddToCollection,
   onAddToDeck,
   onRemove,
+  isAdding = false,
 }) {
   const [ownedQuantity, setOwnedQuantity] = useState(null);
 
@@ -217,11 +218,12 @@ export default function ScannedCardItem({
               <button
                 type="button"
                 onClick={onMarkOwned}
-                className="flex-1 px-3 py-2 rounded text-sm font-medium hover:opacity-80 flex items-center justify-center gap-1"
+                disabled={isAdding}
+                className="flex-1 px-3 py-2 rounded text-sm font-medium hover:opacity-80 flex items-center justify-center gap-1 disabled:opacity-50 disabled:cursor-not-allowed"
                 style={{ backgroundColor: 'var(--accent-gold)', color: 'white' }}
               >
                 <span aria-hidden="true">💎 </span>
-                Mark Owned
+                {isAdding ? 'Adding…' : 'Mark Owned'}
               </button>
               <button
                 type="button"
diff --git a/lib/card-catalog-match.js b/lib/card-catalog-match.js
index e97cd34..ba54d65 100644
--- a/lib/card-catalog-match.js
+++ b/lib/card-catalog-match.js
@@ -1,5 +1,10 @@
 import { sql } from '@vercel/postgres';
 
+import {
+  cardNumbersEquivalent,
+  findPrintingByCollectorNumber,
+} from './card-number-utils.js';
+
 function mapCardRow(card) {
   return {
     id: card.id,
@@ -112,23 +117,50 @@ export async function matchCardInCatalog({
     if (exactResult.rows.length > 0) {
       existingCard = exactResult.rows[0];
     } else {
-      return submitScanForReview(
-        userId,
-        {
-          name: trimmedName,
-          set,
-          setCode,
-          cardNumber,
-          game,
-          cardType,
-          rarity,
-          hp,
-          manaCost,
-          ocrData,
-          scanImageUrl,
-        },
-        []
-      );
+      const setCandidates = await sql`
+        SELECT * FROM cards
+        WHERE LOWER(name) = LOWER(${trimmedName})
+          AND (
+            LOWER(set_name) = LOWER(${set || setCode})
+            OR LOWER(set_code) = LOWER(${setCode || set})
+          )
+      `;
+
+      const normalizedMatch = findPrintingByCollectorNumber(setCandidates.rows, cardNumber);
+      if (normalizedMatch) {
+        existingCard = normalizedMatch;
+      } else {
+        const ambiguousMatches = setCandidates.rows.filter((row) =>
+          cardNumbersEquivalent(row.card_number, cardNumber)
+        );
+        if (ambiguousMatches.length > 1) {
+          return {
+            type: 'disambiguation',
+            card: null,
+            matches: ambiguousMatches.map(mapCardRow),
+            needsUserSelection: true,
+            message: `Found ${ambiguousMatches.length} matches for "${trimmedName}" in that set. Select the correct printing.`,
+          };
+        }
+
+        return submitScanForReview(
+          userId,
+          {
+            name: trimmedName,
+            set,
+            setCode,
+            cardNumber,
+            game,
+            cardType,
+            rarity,
+            hp,
+            manaCost,
+            ocrData,
+            scanImageUrl,
+          },
+          []
+        );
+      }
     }
   }
 
@@ -225,19 +257,7 @@ export async function matchCardInCatalog({
     const hasSpecificPrinting = Boolean((set || setCode) && cardNumber);
 
     if (hasSpecificPrinting) {
-      const printingMatch = await sql`
-        SELECT * FROM cards
-        WHERE id = ${existingCard.id}
-          AND (
-            LOWER(card_number) = LOWER(${cardNumber})
-            AND (
-              LOWER(set_name) = LOWER(${set || setCode})
-              OR LOWER(set_code) = LOWER(${setCode || set})
-            )
-          )
-        LIMIT 1
-      `;
-      if (printingMatch.rows.length === 0) {
+      if (!cardNumbersEquivalent(existingCard.card_number, cardNumber)) {
         const siblingIds = await sql`
           SELECT id FROM cards WHERE LOWER(name) = LOWER(${trimmedName})
         `;
diff --git a/lib/card-import/reconcile-submissions.js b/lib/card-import/reconcile-submissions.js
index 75acfa6..9e6048a 100644
--- a/lib/card-import/reconcile-submissions.js
+++ b/lib/card-import/reconcile-submissions.js
@@ -1,25 +1,8 @@
 import { sql } from '@vercel/postgres';
 
-/**
- * Normalize collector numbers so "015/208" and "15/208" compare equal.
- */
-export function normalizeCardNumber(value) {
-  if (value == null || value === '') return '';
-  const trimmed = String(value).trim();
-  const slashIndex = trimmed.indexOf('/');
-  if (slashIndex === -1) {
-    return trimmed.toLowerCase();
-  }
+import { cardNumbersEquivalent, normalizeCardNumber } from '../card-number-utils.js';
 
-  const numerator = trimmed.slice(0, slashIndex).trim();
-  const denominator = trimmed.slice(slashIndex + 1).trim();
-  const normalizedNumerator = String(parseInt(numerator, 10));
-  if (normalizedNumerator === 'NaN') {
-    return trimmed.toLowerCase();
-  }
-
-  return `${normalizedNumerator}/${denominator}`.toLowerCase();
-}
+export { normalizeCardNumber };
 
 function normalizeGame(value) {
   if (!value || typeof value !== 'string') return null;
@@ -62,7 +45,7 @@ export function submissionPayloadMatchesSet(payload, { game, setCode, setName })
 function cardNumberMatches(catalogNumber, payloadNumber) {
   if (!payloadNumber) return true;
   if (!catalogNumber) return false;
-  return normalizeCardNumber(catalogNumber) === normalizeCardNumber(payloadNumber);
+  return cardNumbersEquivalent(catalogNumber, payloadNumber);
 }
 
 /**
diff --git a/lib/card-number-utils.js b/lib/card-number-utils.js
new file mode 100644
index 0000000..4db6f0e
--- /dev/null
+++ b/lib/card-number-utils.js
@@ -0,0 +1,35 @@
+/**
+ * Normalize collector numbers so "015/208" and "15/208" compare equal.
+ */
+export function normalizeCardNumber(value) {
+  if (value == null || value === '') return '';
+  const trimmed = String(value).trim();
+  const slashIndex = trimmed.indexOf('/');
+  if (slashIndex === -1) {
+    return trimmed.toLowerCase();
+  }
+
+  const numerator = trimmed.slice(0, slashIndex).trim();
+  const denominator = trimmed.slice(slashIndex + 1).trim();
+  const normalizedNumerator = String(parseInt(numerator, 10));
+  if (normalizedNumerator === 'NaN') {
+    return trimmed.toLowerCase();
+  }
+
+  return `${normalizedNumerator}/${denominator}`.toLowerCase();
+}
+
+export function cardNumbersEquivalent(a, b) {
+  if (a == null || b == null || a === '' || b === '') return false;
+  return normalizeCardNumber(a) === normalizeCardNumber(b);
+}
+
+/**
+ * Pick one catalog row when name+set candidates share an equivalent collector number.
+ */
+export function findPrintingByCollectorNumber(candidates, cardNumber) {
+  if (!cardNumber || candidates.length === 0) return null;
+
+  const matches = candidates.filter((row) => cardNumbersEquivalent(row.card_number, cardNumber));
+  return matches.length === 1 ? matches[0] : null;
+}
diff --git a/pages/scanner.js b/pages/scanner.js
index 5b4afb5..618853a 100644
--- a/pages/scanner.js
+++ b/pages/scanner.js
@@ -53,6 +53,7 @@ export default function Scanner() {
   const [bulkTarget, setBulkTarget] = useState('');
   const [isProcessing, setIsProcessing] = useState(false);
   const addingInFlightRef = useRef(new Set());
+  const [addingCardIds, setAddingCardIds] = useState(() => new Set());
   const [sessionDestination, setSessionDestination] = useState(
     () => loadSavedScannerSession().destination
   );
@@ -191,11 +192,14 @@ export default function Scanner() {
     }
 
     try {
+      if (!tryBeginAdding(cardEntry.id)) return;
       await routeCardToDestination(cardEntry, sessionDestination);
       markCardAsProcessed(cardEntry.id, destinationActionKey(sessionDestination));
     } catch (error) {
       console.error('Auto-route failed:', error);
       setAutoRouteError(`Could not add "${cardEntry.name}" to ${sessionDestination.label}. Use the card actions below.`);
+    } finally {
+      endAdding(cardEntry.id);
     }
   };
 
@@ -221,35 +225,56 @@ export default function Scanner() {
     // You could show a toast notification here
   };
 
+  const syncAddingState = () => {
+    setAddingCardIds(new Set(addingInFlightRef.current));
+  };
+
+  const tryBeginAdding = (cardId) => {
+    if (addingInFlightRef.current.has(cardId)) return false;
+    addingInFlightRef.current.add(cardId);
+    syncAddingState();
+    return true;
+  };
+
+  const endAdding = (cardId) => {
+    addingInFlightRef.current.delete(cardId);
+    syncAddingState();
+  };
+
   // Individual card actions
   const addSingleCardToOwned = async (card) => {
-    if (addingInFlightRef.current.has(card.id)) return;
-    addingInFlightRef.current.add(card.id);
+    if (!tryBeginAdding(card.id)) return;
     try {
       await addToOwnedCards(card);
       markCardAsProcessed(card.id, 'owned');
     } catch (error) {
       console.error('Error adding card to owned:', error);
     } finally {
-      addingInFlightRef.current.delete(card.id);
+      endAdding(card.id);
     }
   };
 
   const addSingleCardToCollection = async (card, collectionId) => {
+    if (!tryBeginAdding(card.id)) return;
     try {
       await addToCollection(card, collectionId);
       markCardAsProcessed(card.id, 'collection');
     } catch (error) {
       console.error('Error adding card to collection:', error);
+    } finally {
+      endAdding(card.id);
     }
   };
 
   const addSingleCardToDeck = async (card, deckId) => {
+    if (!tryBeginAdding(card.id)) return;
     try {
       await addToDeck(card, deckId);
       markCardAsProcessed(card.id, 'deck');
     } catch (error) {
       console.error('Error adding card to deck:', error);
+    } finally {
+      endAdding(card.id);
     }
   };
 
@@ -265,17 +290,26 @@ export default function Scanner() {
 
       for (const card of cardsToProcess) {
         if (action === 'owned') {
-          if (addingInFlightRef.current.has(card.id)) continue;
-          addingInFlightRef.current.add(card.id);
+          if (!tryBeginAdding(card.id)) continue;
           try {
             await addToOwnedCards(card);
           } finally {
-            addingInFlightRef.current.delete(card.id);
+            endAdding(card.id);
           }
         } else if (action === 'collection' && target) {
-          await addToCollection(card, target);
+          if (!tryBeginAdding(card.id)) continue;
+          try {
+            await addToCollection(card, target);
+          } finally {
+            endAdding(card.id);
+          }
         } else if (action === 'deck' && target) {
-          await addToDeck(card, target);
+          if (!tryBeginAdding(card.id)) continue;
+          try {
+            await addToDeck(card, target);
+          } finally {
+            endAdding(card.id);
+          }
         } else {
           continue;
         }
@@ -610,6 +644,7 @@ export default function Scanner() {
                           onAddToCollection={(collectionId) => addSingleCardToCollection(card, collectionId)}
                           onAddToDeck={(deckId) => addSingleCardToDeck(card, deckId)}
                           onRemove={() => removeScannedCard(card.id)}
+                          isAdding={addingCardIds.has(card.id)}
                         />
                       </li>
                     ))}
diff --git a/test/lib/card-import-reconcile-submissions.test.js b/test/lib/card-import-reconcile-submissions.test.js
index ee7b9a6..f8a7de5 100644
--- a/test/lib/card-import-reconcile-submissions.test.js
+++ b/test/lib/card-import-reconcile-submissions.test.js
@@ -1,18 +1,10 @@
 import { describe, expect, it } from 'vitest';
 
 import {
-  normalizeCardNumber,
   pickCatalogCardForPayload,
   submissionPayloadMatchesSet,
 } from '../../lib/card-import/reconcile-submissions.js';
 
-describe('normalizeCardNumber', () => {
-  it('treats leading-zero numerators as equivalent', () => {
-    expect(normalizeCardNumber('015/208')).toBe('15/208');
-    expect(normalizeCardNumber('15/208')).toBe('15/208');
-  });
-});
-
 describe('submissionPayloadMatchesSet', () => {
   it('matches by set code or set name for the imported game', () => {
     const imported = { game: 'pokemon', setCode: 'sv10', setName: 'Perfect Order' };
diff --git a/test/lib/card-number-utils.test.js b/test/lib/card-number-utils.test.js
new file mode 100644
index 0000000..244437d
--- /dev/null
+++ b/test/lib/card-number-utils.test.js
@@ -0,0 +1,35 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  cardNumbersEquivalent,
+  findPrintingByCollectorNumber,
+  normalizeCardNumber,
+} from '../../lib/card-number-utils.js';
+
+describe('normalizeCardNumber', () => {
+  it('treats leading-zero numerators as equivalent', () => {
+    expect(normalizeCardNumber('015/208')).toBe('15/208');
+    expect(normalizeCardNumber('15/208')).toBe('15/208');
+    expect(normalizeCardNumber('18/88')).toBe('18/88');
+  });
+});
+
+describe('cardNumbersEquivalent', () => {
+  it('matches normalized collector numbers', () => {
+    expect(cardNumbersEquivalent('015/208', '15/208')).toBe(true);
+    expect(cardNumbersEquivalent('18/88', '015/208')).toBe(false);
+  });
+});
+
+describe('findPrintingByCollectorNumber', () => {
+  it('returns the sole matching printing', () => {
+    const match = findPrintingByCollectorNumber(
+      [
+        { id: 1, card_number: '18/88' },
+        { id: 2, card_number: '19/88' },
+      ],
+      '018/88'
+    );
+    expect(match?.id).toBe(1);
+  });
+});