Details apparently came out of the recent Puletua court case, that show he has two contracts. One with Salford and one with another of Koukash's companies. So it looks to be the same dual contract trick that other clubs have been alleged to utilise and that Keith Senior was proven to have when he signed for Crusaders and wanted the RFL to take action there.
It's a practice that's been (allegedly) going on for a while at some clubs, it's just that now there's a degree of proof because of the Puletua case bringing it to light.