Hello Browncoat,
The identical cards are already being sorted together. Do you mean 6,7,8 star version of a card set being grouped together like email threading, where lower version get's attached to higher version if present, otherwise show up in the natural position? I don't think in-game sorting offers such sorting either but it can be looked into a card bank option... Would any player who uses the card bank would prefer such grouping.
Best Regards,
Playmage Support