No, do delete the 2h file if it was produced from a different trn file.
Generally dom3 ignores 2h files from different turns. But if the turn number is the same, but it's from a different trn file (as happens after rollbacks and so on), dom3 can get itself in a massive confusion.
On the other hand, if you delete a 2h file that you're meant to be using, you just lose a load of work I guess.
