Okay.
I know there are lots of glitches they're working on, and I've looked through the last few pages to see if anyone else is having this problem, and so far no one has.
Like I said I might be doing this wrong, but I dont think so.

I am working on "The House Always Wins, I" and "II"

*Spoilers?*

I confront Benny about the coin, he locks me in the suite, I go to find him, talk to Yes Man and so on. So I go back to House and he tells me what to do. I get confronted by one of Ceasar's men giving me the Mark Of Ceasar and to join him. After HOURS of searching on how to get to the The Fort (I do realize I'm an idiot) I get to the docks and am immediately get ambushed and railed. So I put on some Legionnaire clothes and walk to the dock where I take the boat and all that. I get to Ceasars tent, and find Benny tied up. So I, being the "paragon" untie him. Then Ceasar's men kill him. I figure the coin is on his body, and its no where to be found. So I talk to Ceasar. It zooms on his face, like its going to talk to him, but then zooms back out. So I save, in a new slot, and try again. This time I leave Boone and E-DE behind. I try the docks, Die. Disguise, go through that whole mess all over again, and the same thing happens. I try killing Benny myself... Nada. Everything I've tried, and still no coin.

I dont care about talking to Ceasar (I actually tried killing him once..) because I'm already Hated with them.
All I want is the chip and to continue with this quest.

If anyone knows why its not working or has had this happen to you, please let me know. Thanks!

Caesar has the chip. You have to talk to him to get it. Killing him and looting his corpse should work too.

When you got the Mark of Caesar, your rep with them gets reset to Neutral if it's less. Did you happen to massacre any Legion while you were out and about?

EDIT: Damn forum, making me double post.

I did try to kill him. But its either that I'm not high enough level or something and i just die. So, okay.. I'll try that. IF I can talk to him that is... lol.

It is pretty hard to kill him since he and all his cohorts are so numerous, powerful, and armored.

Yeah, I had to use 2 of my mini-nukes with a few headshots from a hunting shotgun (with the Shotgun Surgeon perk) to bring them all down. I was about level 27 with T51b power armor as well. So he isn't easy to take down. Also, beware of the guards, they packed ballistic gloves for me and did large amounts of damage.

They went overboard with melee weapons and unarmed which end up being the ultimate weapons. They also went overboard with the damage thresholds.