What do I do when adding a CD single that has more than one part? i.e has CD single pt 1, pt 2 and pt 3, each with different tracks?

Do I add one version, and put the alternate tracklists in the notes, or submit 3 separate entries?

What do you mean with "parts"? Like a concept album with different conceptual segments in the album or release with two,three or even four discs/tapes?

I mean when they release a CD single with 2 or 3 different versions (or parts), each containing the main track, but with different bonus tracks.

Example: The Almighty "Do You Understand"

http://members.chello.at/rudolf.munduch/understand.htm

Ah I see... I remember that we discussed it once, but how the mods decided is something I do not recall anymore; it was not recent. You will have to wait until a mod sees this thread or someone familiar with this topic; Evenfiel might have more information on this issue ... I am pretty sure he does.

Add one version (the most common, if possible, or the first one) and mention the others on the additional notes.

OK, will do. Thanks for that.

This isn't too uncommon actually. The Cure released some singles that were officially the same thing, but with different coverart and different tracklisting. One had the A-side and some B-sides, while the other had remixes of the A-side with more B-sides. It's all confusing...

Surely if they have differing tracks they're listed as seperate items though?

Metallica's 'The Unofrgiven II' has part I & II listed as seperate on the archives.

Nope. Metallica's page is an awful mess, with multiple versions of the same release. That's akin to having every reissue of an album as a separate entry.

Unfortunately, one will find that this often ends up being the case for very popular or iconic bands with huge catalogs. The pages often need to be cleaned periodically.