'Pawn Stars' Cast FURIOUS Over 'Cajun' Spin-off

The debut of the new "Cajun Pawn Stars" was a huge hit with the History Channel ... but TMZ has learned the guys at the original "Pawn Stars" show are PISSED because they had no idea it was being made.

Sources close to Left Field Pictures -- the production company behind "Pawn Stars" -- tell us the Vegas crew feels "blindsided" ... because they only learned about the show a few weeks ago ... when the network made the official announcement.

We're told Chumlee, Rick, Corey and the Old Man insist they were promised by the network that no "Pawn Stars" spin-off shows would be made of any kind ... and now feel like they were betrayed.

Sources say the guys are "really hurt" by the whole thing and feel like the new show is a "total knock-off" -- but their beef is with the network ... and NOT with the cast of the new show.

Pretty shocking behavior by the network -- considering "Pawn Stars" is the number one show on History and one of the highest rated shows on cable.