Pull Request merge bug?

Hi,
Two members of our development team have, at the same time or very close it, merged two different pull requests.

The result is strange. Both merged pull requests show that they have been merged at the same commit. Looking at the commits shows a different result.

These are the Pull Requests:

There are the merge commits:

This has happened previously, and it only appears to happen when the pull requests are merged at the same time or close to it.

Marin