I recently ran into a similar situation. There were 4 .mer's on the terminal, and an outside contractor had done the last revision to the software. In addition to not using our standard naming convention for revision changes, he also did not remember to restore the runtime security for the application after he had done an upload/restore. On this application there was a "Goto Config" button on the main screen, with security-controlled visibility, but because of the scrambled security info, was useless
So what I had to do, was upload all 4 mer's. I took screen shots of all the screens running on the terminal. I then compared the development screens of all 4 applications to the pics I had to find one that matched. Luckily, one of the 4 actually had two new screens that the others did not.
Unfortunately, this tedious method won't always work for determining current version. If the previous programmer only changed tags on objects, or object properties, visibilities, etc, or added invisible buttons, or changed passwords/added users, things like that, then you can't determine any of that just by a visual examination of the running program.
I would like to see a feature added to the terminals that would show you the last loaded application on the config screen.