I've never tried doing something like this before, but this seems to work. Set yourself to overwrite existing files and try this code out. Just have someone send you a small text file once, then another one with the same filename and different text in it. Verify that they are different in your download folder afterwards. The original will now have _2 in the filename. Note that this is just a basic script and isn't designed to handle when you already have a _2 file.
ctcp *:DCC Send *:*:{
if ($exists($filename)) {
var %ext = $gettok($filename,$gettok($filename,0,46),46)
rename $filename $remove($filename,. $+ %ext) $+ _2. $+ %ext
}
}
So...
filename.txt is in your download folder and someone sends another filename.txt to you. the original is renamed to filename_2.txt and the new one is named filename.txt. It shouldn't be too difficult to have it check prevent problems when a _2 is already there. I just don't have time to mess around with it right now.