I don't know what the proper thing to do is, but here's my experience.

DISCLAIMER: Anything I say here might be screwed up, as I didn't really take detailed notes, and my memory might not be correct.
I started with version 4.0 something. When 6.0 Platinum came out, I downloaded and installed it, without uninstalling 4.0. Of course, I had to enter the new activation code for the 6.0 Platinum. Later, when I tried to run 4.0 for some reason, it acted like it was an unregistered version. No big deal, since I didn't actually need to do anything in it. I don't recall if I re-entered my old 4.0 activation code, or just ignored the problem (which means it would probably act like a "trial" edition?)

When the 6.0a update came out, I decided I would finally uninstall 4.0 before installing 6.0a. After uninstalling 4.0 -- and before installing 6.0a, I think -- I think my 6.0 then acted like an unregistered version, and I had to enter the activation code again.

Like I said, I might not be remembering this correctly, but I never had any real problems -- just had to re-enter activation codes for one or the other, or maybe both. (Perhaps these products share a single registry item for activation code?)

By the way, VMS 6.0 will read your 4.0 projects with no problem, but will warn you when you save from 6.0 that the project will no longer be compatible with 4.0. If this is a problem for you, be sure you save a copy of your project in 4.0 format, though I don't know why that would be an issue.

Also, VMS (regular and platinum) are presently at release 6.0a, and DVDA Studio is at 3.0a. If you purchased the upgrade on disc (instead of just download), you might want to double-check that you get 6.0a. If not, head over to the updates page, and download 6.0a platinum, rather than installing from your CD.

Tim L