diff --git a/packages/backend/src/lib/adapters/instagram.test.ts b/packages/backend/src/lib/adapters/instagram.test.ts
index 26a503c..32b773a 100644
--- a/packages/backend/src/lib/adapters/instagram.test.ts
+++ b/packages/backend/src/lib/adapters/instagram.test.ts
@@ -159,6 +159,21 @@ describe("InstagramAdapter", () => {
       expect(items[0].id).toBe("high");
       expect(items[1].id).toBe("mid");
     });
+
+    it("deduplicates items by id", async () => {
+      mockFetch.mockResolvedValueOnce({
+        items: [
+          { code: "AAA", caption: "First", user: { username: "a" }, like_count: 8000 },
+          { code: "AAA", caption: "First dup", user: { username: "a" }, like_count: 8000 },
+          { code: "BBB", caption: "Second", user: { username: "b" }, like_count: 3000 },
+        ],
+      });
+
+      const items = await adapter.fetchTrending(20);
+      expect(items).toHaveLength(2);
+      expect(items[0].id).toBe("AAA");
+      expect(items[1].id).toBe("BBB");
+    });
   });
 
   describe("fetchDetail", () => {
diff --git a/packages/backend/src/lib/adapters/instagram.ts b/packages/backend/src/lib/adapters/instagram.ts
index 1ddfac9..522a1a4 100644
--- a/packages/backend/src/lib/adapters/instagram.ts
+++ b/packages/backend/src/lib/adapters/instagram.ts
@@ -33,11 +33,16 @@ export class InstagramAdapter implements PlatformAdapter {
       }
     }
 
+    const seen = new Set<string>();
     return items
       .map((item: unknown, index: number) =>
         this.mapToContentItem(item as Record<string, unknown>, index)
       )
-      .filter((item) => item.like_count != null && item.like_count >= 100)
+      .filter((item) => {
+        if (seen.has(item.id)) return false;
+        seen.add(item.id);
+        return item.like_count != null && item.like_count >= 100;
+      })
       .sort((a, b) => (b.like_count ?? 0) - (a.like_count ?? 0))
       .slice(0, count);
   }