Join private group: Admin get a lot of the same notifications

Hello. Steps to reproduce:
1) User1 send request to join private group
2) User1 reject his request to join private group
3) User1 send request to join private group again
4) User1 reject his request to join private group
5) User1 send request to join private group again
6) User1 reject his request to join private group
Result: User2 (group's admin) get 3+ notification about this user1 (like on the screenshot).
Expected result: after "self rejection" (by user1) notificationa should be auto deleted.

Thanks.