incorrect file size sometimes

On some of my files the file size displayed is incorrect. I tried unchecking “Cache retrieved file sizes” and re-uploading the files but that didn’t fix it. So far, this has only happened on my files with shorter names, for example: 2015-plan, all of which have supplemental files with similar names, like 2015-plan-cover and 2015-plan-ch1. What seems to have resolved the issue is adding more to the file name, like 2015-plan-adopted, and then the file size is correct. For the most recent occurrence, I realized the displayed file size for the plan was the same as the cover image, which was about 80 kb, instead of the accurate file size of ~15 MB. It seems like I’ve found a solution through using longer file names, but I just wanted to throw this issue out there in case there is a better approach. Thank you!