All you have to do is simple.
Just set isobuster up as it is supposed to be, so the dates appear correct.
Then put the dumped disc in your drive, and select that dump on redumps main page, check to see if the dates are different, if not don't do anything, if some are different you need to post what the differences you find are, in the fixes section.
Also sometimes when the date is set either way in isobuster, the date of the exe file remains the same.
Othertimes the exe date will be different, that basically means you may find some that the date seems to be correct, it just means that setting the date either way its the same, just don't automatically assume if you see one and the date is the same, that it means you had the date set right in the first place.
Also what do you mean by (reformatted since)?