Yes, you would either need 2 separate PA forms or 2 SR forms. If they contain sampled works, and it's an album, then I would use form SR.
Say there are 4 artists on the album, but they appear separately on many tracks. For this example, lets say their names are John, Mike, Chris, and Alex. Lets assume that John makes all the beats, to make this easier.
Say there are 18 songs on the album. John and Mike are on 4 together, Chris and Alex are on 5 songs together, John, Mike, Chris and Alex have 3 songs together, Mike, Chris and Alex have 3 songs together, John has 2 solo tracks, and Alex has 1 solo track.
This is how it would break down:
SR Form 1: (4 songs) John and Mike
SR Form 2: (5 songs) Chris and Alex
SR Form 3: (3 songs) John, Mike, Chris, Alex
SR Form 4: (3 songs) Mike, Chris, Alex
SR Form 5: (2 songs) John
SR Form 6: (1 song) Alex
Total: (18 songs), 6 Forms, $180.00
However, if you wanted to divide it up by the group, it's only $45 each for the group, and if the beatmaker wants in, it's $36 each.
I think there are loopholes, but I can't guarantee that it would give you the copyright protection that you need to hold up in court if someone were to steal your music.
Hope this helped.
-Hypno