Yes, I have a 9.1 disc that is just an updater - it looks exactly the same as the retail 9.1 disc (white background, big orange "9" etc) except it says "Mac OS 9.1 Update CD" on it. I think the 9.1/9.2 update discs may have come with various versions of OS X as you needed the update for the Classic Environment to work (possibly the instant up-to-date packs, as the full retail versions of 10.0 and 10.1 came with a full 9 disc too).
I've never seen one of these discs containing all of the Apple updates though, only ones for specific OSes, so maybe they didn't have those over here.