almost a bug report, but since an experienced user should probably know to work around it maybe just a feature request…
when the module designer is working in the module editor and selecting images to use (for maps or counters, probably other categories too) sometimes they might have the same filename but come from a different file directory. well… Vassal just seems to dump them all into the same directory, and (the issue) does not politely tell the module designer that there is another image with the same filename already being used for the game - alerting the md to the problem. so when the module loads it loads image files which may not be the ones the designer intended.