The Mints have often fell back on using retired Dies (mainly Reverse Dies) to finish production runs due to premature Die Failures that exhausted the Dies made for that specific year. Therefore, it is possible that a coin struck during a certain year and another coin struck during a different year, could have been struck by the same Die. I don't think that is the case with your' two Dimes! A crack in the Die cannot be fixed. However, the Mints sometimes modify Dies to correct issues that causes premature Die Failures. To do so, is a big thing with the Mints which has to be researched, discussed and approved as making changes (modifications) to Dies during a production year, creates Varieties due to the modifications making differences in the Dies and the coins struck by them.
Frank