Yes...BUT...unlike Total Rewards, the MILF system deactivates any old cards, once you get new ones printed. The most I can get issued at one time is two cards. And, sure enough, if I try the old card in my backpocket [which worked prior to the issuance of the new cards], it no longer works. And I totally understand why they do this. They don't want multiple people playing on your card, giving you a disproportionately high tier status that you haven't (theoretically) earned.
Total Rewards, on the other hand, has no problem issuing cards and having them all work. So when I was in Vegas between Christmas and New Year, last month, there were 4 of us playing on my TR card.
In my humble opinion, I see nothing wrong with people earning points on my card. It's their money they're into the slot machines there (See what I did *there*?) So the points I'm getting is, essentially, a referral fee paid to me by the casino for bringing friends into town to gamble in their casino!