In the situation of program version merging In general:
Each are different programs, no one would say that photoshop4 is photoshop10.
each can have different features and different problems.
For some programs the versions are night and day different in problems, interface changes even, and existance of items.
for some programs there are only minor changes.
For a user, the NEWer the "latest version", is the latest change to the user:
These tags would be the Least "used", and possibly the most important difference at that Time
A view of them would suggest that the "latest version" Tag is unused and useless, so easy to dump into the pile of "that program".
That could be an error of assumption
The opposite is usually true, the new item is the new change is the most active discussion at the time.
As the seperation of program versions is layed out on a normal Forum, it would often look like this:
Program V1-V8 (pile of old stuff and some rare new questions)
Program V9 (Piles of old and new questions, still active I/O between users)
Program V10 (less questions, still active I/O between users)
Program V11 (hardly any questions, just came out)
With the older questions uncerimoniously dumped raw into the Old bucket as new versions came along. The Old bucket could be just [PROGRAM] and would still be arbitrarily applied.
That same pattern should be able to be used here. Version still in active discussion would be maintained seperate. Versions not in active use, by default, would not have new tags created (good luck with that).