I don't have too much time to explain the concept of this mix. In a nutshell, this mix is a cover mix. As far as I know, this is the first mix that I've heard of that is a "cover" of another mix. Below is the description as described by the Grand Groove DJ's.
"Grand Groove DJ's: This mix is inspired by the work of legendary New York mixtape DJ’s G-BO THE PRO AND DOUBLE R, with special thanks to our homie DJ NEIL ARMSTRONG for putting us up on game. Awhile back Royale showed me G-Bo the Pro and Double R #21. It was an instant hit receiving HEAVY rotation in the car. Roy then suggested the idea that we re-do the tape, a cover per se, adding our own Grand Groove touches throughout. Covering a mixtape, who does that!? So that’s what we did! We re did the B Side of the tape and flipped the cover too (thanks to Committee Design). While we kept a lot of the original tracklisting we also included some of our own personal favourites and original blends that we felt would fit in the mix. Here’s the original cover and tracklisting…"
School R&B Flavas - Mixed by Grand Groove DJ's (download)