[0.96] A whole lotta awesome

Isn't it obvious? They only changed them to Evolving ring 2 so you coulnd't use the rings from the first event in the levelling process. So they're probably unstackable.

That's a lot of work for a trivial concern.
Tradeable rings from the last event would not be upgradeable anyway. Gaga's scripts for upgrading only recognize the untradeable versions of rings.
There are very few people with untradeable rings from the first event, and I really don't see the harm in letting them continue from where they got stuck (presumably by missing that one specific day of the end of the event).