Lightroom adding suffix to files, of same name with different extension, shouldn’t happen

have a folder of JPG and Tif files named the same, allowed in Windows as have different extensions, but when I publish them, the Tif files get a suffix of '2' added, shouldn't happen. Have all renaming options etc turned off, asked and looked everywhere for a reason, not to serious but annoying. I use Jeffrey’s “Folder Publisher” Lightroom Plugin, according to a post on his blog, it's Lightroom that does this. This could be.a BUG as Windows allows same name files with different extensions, there's no reason for Lightroom to add the suffix.