Yep. They actually classify 'Power of the Dollar' it as an EP, not a mixtape. Came out in 2000, 3 years before his first LP.
Ghetto Qu'ran was also featured on the mixtape, Guess Who's Back, which had some heavy hitter producers like Trackmasters, L.E.S. and DJ Clark Kent.
The President of Motown, Berry Gordy Jr., would regularly have several different artists record the same songs using the original backing tracks, and then release the one(s) he liked best.
Her are some alternate recordings of various Motown songs...