Views Template Suggestions When There are Duplicate Filenames
You could look and see in your theme registry by dpm-ing in theme_registry_alter() or by turning on devel and visiting /devel/theme/registry and seeing what entry is pointing to what file.

If you don't want to do that on production you could do it locally first and then grab the production database locally. 

I would imagine that the registry was rebuilt between the two sites and the first time it picked up one of the files and the second time the other since I don't know of a designed hierarchy for two files in the same level directories in a theme folder.

Don't upvote - this is a speculative answer.