diff --git a/test/api/unit/models/userNotification.test.js b/test/api/unit/models/userNotification.test.js
index 772e8dba8f..8e9405ee0a 100644
--- a/test/api/unit/models/userNotification.test.js
+++ b/test/api/unit/models/userNotification.test.js
@@ -50,5 +50,59 @@ describe('UserNotification Model', () => {
       expect(safeNotifications[0].type).to.equal('NEW_CHAT_MESSAGE');
       expect(safeNotifications[0].id).to.equal('123');
     });
+
+    it('removes duplicate STREAK_ACHIEVEMENT notifications', () => {
+      // Fixes issue #13325 - Users receiving duplicate streak achievement notifications
+      const notifications = [
+        new UserNotification({
+          type: 'STREAK_ACHIEVEMENT',
+          id: 123,
+          data: {},
+        }),
+        new UserNotification({
+          type: 'STREAK_ACHIEVEMENT',
+          id: 456,
+          data: {},
+        }),
+        new UserNotification({
+          type: 'CRON',
+          id: 789,
+          data: {},
+        }), // different type, should be kept
+      ];
+
+      const safeNotifications = UserNotification.cleanupCorruptData(notifications);
+      expect(safeNotifications.length).to.equal(2);
+      expect(safeNotifications[0].type).to.equal('STREAK_ACHIEVEMENT');
+      expect(safeNotifications[0].id).to.equal('123');
+      expect(safeNotifications[1].type).to.equal('CRON');
+      expect(safeNotifications[1].id).to.equal('789');
+    });
+
+    it('handles multiple STREAK_ACHIEVEMENT duplicates correctly', () => {
+      // Test case: 3 duplicate STREAK_ACHIEVEMENT notifications
+      const notifications = [
+        new UserNotification({
+          type: 'STREAK_ACHIEVEMENT',
+          id: 111,
+          data: {},
+        }),
+        new UserNotification({
+          type: 'STREAK_ACHIEVEMENT',
+          id: 222,
+          data: {},
+        }),
+        new UserNotification({
+          type: 'STREAK_ACHIEVEMENT',
+          id: 333,
+          data: {},
+        }),
+      ];
+
+      const safeNotifications = UserNotification.cleanupCorruptData(notifications);
+      expect(safeNotifications.length).to.equal(1);
+      expect(safeNotifications[0].type).to.equal('STREAK_ACHIEVEMENT');
+      expect(safeNotifications[0].id).to.equal('111'); // Keep first one
+    });
   });
 });
diff --git a/website/client/src/components/notifications.vue b/website/client/src/components/notifications.vue
index 2639680d48..27d90d502a 100644
--- a/website/client/src/components/notifications.vue
+++ b/website/client/src/components/notifications.vue
@@ -330,6 +330,7 @@ export default {
       handledNotifications,
       isInitialLoadComplete: false,
       pendingRebirthNotification: null,
+      lastShownStreakCount: null, // Track last shown streak to prevent duplicates
     };
   },
   computed: {
@@ -737,6 +738,13 @@ export default {
             }
             break;
           case 'STREAK_ACHIEVEMENT':
+            // Client-side deduplication: prevent showing duplicate streak achievements
+            if (this.lastShownStreakCount === this.user.achievements.streak) {
+              // Same streak already shown, skip this notification
+              break;
+            }
+            this.lastShownStreakCount = this.user.achievements.streak;
+
             this.text(`${this.$t('streaks')}: ${this.user.achievements.streak}`, () => {
               this.$root.$emit('bv::show::modal', 'streak');
             }, this.user.preferences.suppressModals.streak);
diff --git a/website/server/models/userNotification.js b/website/server/models/userNotification.js
index dc270231bf..dfaf4462e4 100644
--- a/website/server/models/userNotification.js
+++ b/website/server/models/userNotification.js
@@ -143,6 +143,16 @@ schema.statics.cleanupCorruptData = function cleanupCorruptNotificationsData (no
     return false;
   });
 
+  // Remove duplicate STREAK_ACHIEVEMENT notifications
+  // Deduplicates by keeping only the first occurrence of STREAK_ACHIEVEMENT notification
+  filteredNotifications = _.uniqWith(filteredNotifications, (val, otherVal) => {
+    if (val.type === 'STREAK_ACHIEVEMENT' && val.type === otherVal.type) {
+      // If both are streak achievements, they are duplicates
+      return true;
+    }
+    return false;
+  });
+
   return filteredNotifications;
 };