Does Richard Roma have a hidden agenda?

One of the many surprises in David Mamet's excellent play Glengarry Glen Ross is Ricky Roma's revelation of his crafty and venal character at the very end. Roma has pretended to share in Shelly Levene's triumph when the aging salesman bursts into the office and announces that he just finished selling eight units of Mountain View for $82,000 and is "back on the board." Roma wants to hear all about the sale. He keeps calling him "Levene the Machine," praising and flattering him, defending him from Dave Moss, and finally suggesting that he would like to go into partnership with Shelly. He shows what he has in mind in the following:

"Shel: I want to talk to you. I've wanted to talk to you for some time. For a long time, actually. I said, "The Machine, there's a man I would work with. There's a man. . . . You know? I never said a thing. I should have, don't know why I didn't. And that shit you were slinging on my guy today was so good . . . it . . . it was, and, excuse me, 'cause it isn't even my place to say it. It was admirable . . . it was the old stuff. Hey. I've been on a hot streak, so what? There's things that I could learn from you. You eat today?"

But then, near the very end of the play, when Shelly is pushed into the side room to make a formal confession to the cop named Baylen, Roma says:

"Williamson: listen to me: when the leads come in . . . listen to me: when the leads come in I want my top two off the list. For me. My usual two. Anything you give Levene . . . . Do you understand? My stuff is mine, his stuff is ours. I'm taking half of his commissions--now, you work it out."

Roma obviously doesn't know that Shelly is going to be taken out in handcuffs and will lose his license and probably go to jail. What Roma has in mind is accompanying Shelly on his "sits" but keeping his own sits all to himself. All his flattery has been leading up to a selfish proposition. He thinks Shelly will go for the idea of a partnership because Shelly has been running cold and Roma has been running hot. Roma is still young. Shelly is getting old and demoralized, not unlike Willy Loman in Arthur Miller's Death of a Salesman.
Eventually Shelly would have found out that Roma was not sharing his own leads with him but helping himself to half of Shelly's; in the meantime Roma might have made a lot of extra money, and he might have even been able to continue the partnership arrangement if he had proved Levene could make more money with his help than he could make going out on sits by himself.
The way Roma proposed to cheat Shelly is similar to the way Dave Moss cheated Shelly on the sale of the the Glengarry leads to Jerry Graff. Shelly stole them but Moss took them to Graff and gave Shelly $2500, probably keeping around $5000 for himself. Moss was planning to do the same thing with Aaronow, but Aaronow backed out and Moss enlisted Shelly at the last minute.