Single commit displayed twice in MR discussion tab

Summary

I created a MR and after some discussion pushed another commit to the branch to be merged. In the commits tab the last commit is correctly shown only once. But in the discussion tab the commit appears twice with identical information but as different notes.

Steps to reproduce

In another repository I wasn't able to reproduce this. Also on my lokal instance and my productive GitLab CE 11.11.1 I wasn't able to make this happen again.

What have I done in the repo on GitLab.com:

• forked, pulled and created a new branch locally
• did some changes, added them and pushed via git 2.21.0 in shell
• after some discussion inside the MR I changed some more lines of code and pushed them in shell again
• in the MR the commit is listed twice in the discussion tab

Example Project

First commit: https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/113#note_177839216
second commit: https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/113#note_177839512

What is the current bug behavior?

I pushed one commit but in the discussion tab the same commit is displayed twice.

What is the expected correct behavior?

One commit should be displayed only once without duplicates.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com