Confusing git log --- First time bug submission please advise on best practices

My co-worker has an inconsistent git log output. Please see that attached files for output (I've made a best effort to remove confidential info from them).

Comparing the two log commands we can see that master and originssh/master have a shared common commit at

    <John Doe> (4 hours ago) d85832d
  More pom fixes

The top commit for originssh/master and the second to top for master.

I would expect that both logs would share an _identical_ history from that commit onward. But the log for master contains the following

  <Jeremy Doe> (27 hours ago) 239ea21  (my-work)
  renamed class

  <Jeremy Doe> (28 hours ago) 27750b2
  Merge branch 'master' of
http://githost.companyname-dev.local/trading-development/sports-container-framework

and

  <Jeremy Doe> (2 days ago) a933acb
  white space changes

  <Jeremy Doe> (2 days ago) b5e51e7
  Merge branch 'master' of
http://githost.companyname-dev.local/trading-development/sports-container-framework

  <Jeremy Doe> (2 days ago) 3a0f787
  removed public methods

  <Jeremy Doe> (2 days ago) 4e91130
  added the xml deserialisation

None of which appear in the originssh/master log. Is there a scenario in which this is expected. It was my understanding that any two commits with the same hash have exactly the same history.

Thanks for your time.

Technical details:

He is using the Windows git client version 1.8.5.2.msysgit.0 Running on Windows 7 Every command was run through git bash

Background:

He previously had tortoise-git installed, but I had him uninstall it to solve some ssh problems While uninstalling tortoise-git we also reinstalled git - I don't know what the previous version of git was.

Output of

    git branch -avv
    * master                   6833fd4 Completed merge
      my-work                  239ea21 renamed class
      remotes/origin/HEAD      -> origin/master
      remotes/origin/master    f269789 Cleaning up GIT step 1
      remotes/originssh/master d85832d More pom fixes

The background on the originssh remote branch is that his origin uses an HTTP url which wasn't allowing him to push a large commit. I helped him to create originssh to allow the push to be made.