Now I’ve read the original full color manga of this series back in the mid nineties. I’ve bought volume 1 which tells half the story. I assume volume 2 will tell the second half of the story.
So whats in the third volume? Stories that had not been released in the comics that I was reading before?
It’s an extra story that wasn’t printed in English before. The Street Fighters travel to an island and fight clone versions of themselves. Ryu vs, Ryu, Ken vs. Ken, Chun-Li vs. Chun-Li, and Guile vs. Guile. Basically they fight their second player versions, and have mirror matches if you will.
The entire book is worth purchasing because Ryu accidentally touches Chun-Li’s breast and she punches him so hard he flies on top of a building. 
The first two volumes are un-edited and un-flopped like the colored versions you purchased before. They also have character relationship charts, statements from Masaomi Kanzaki and new covers that he drew himself. You may want to check those out too.