Funcrusher
All Star
A guess.
That was the original recording with one verse, no diss. Dre leaves, somehow Blackstreet ask him to do a feature, fortuitously they've also independently flipped the same sample into a track very much like the one Pac worked on with a ex friend of theirs called Aaron. Pac, inspired randomly and for absolutely no reason to do with the above events, tacks on a second verse going at Dre talking about non players on stolen beats that don't belong to them and adds it to his album.
Then, in a totally unrelated coincidence, Blackstreet have also reused another Pac sample from another planned single. Its a miracle!
Like I said, its a guess but the odds of that happening naturally are slim. Dre is the common link, the petty would be comprehendable in that situation given how DR was going at him and he needed to keep his name out there. I think that was Dres beat he made for Danny Boys album, he took it with him, Jimmy shopped it to Blackstreet (also on Interscope), Pac heard about it, added the diss, got C&D'd because its Dres beat then remade the track for 7 Day Theory.
That and the difference between the leaked version linked and the retail has that signature Dre polish that makes his work very noticeable, even if uncredited.
Never heard this version instantly like it better than the album version, always hated that oooow part weaved into the beat.