What shaft is it that you need to install one piece rings? If its conventional just get a different set of rings or cut yours. When I say "size" , I mean shrink them back down to the bore size. Teflon is stupid and has NO memory so if its stretched it just stays that way.
use a long socket to hold the teflon ring on... then with a sharp x-zacko knife, cut the ring at angle to scarf cut them. Longer scarf cut the better. Check for fitment and you may need to size them as with 1 piece use