Same here - applied SP3, now SP2 shows as available in Veritas Update. On two servers at one client, one server at another.
I think I've seen this behavior before, months or years ago, probably on an older version - maybe v9? I have a vague memory that the solution involved re-aplying the older SP, then hacking some registry settings to make sure the next SP would recognise it. But don't rely on that!
Regards
William