I've done it before, never got cancelled. Sometimes if I know who is dining where, I will book the one I am not going to in someone else's name, but not always. I have held, for example, a 7:15pm at Crystal Palace for 4 and a 7:20pm at Liberty Tree Tavern for 3, both in my name, when traveling with a party of 7 all booked in the same 2-br villa.
What they will do is ask you, 'You seem to have booked two reservations within an hour of each other, if these are both for the same party, please delete one.' What they mean is, we don't want you booking three or four options for the same folks, but if these are different people then ok.
If you're worried about it, book them in your name and one of the other people's names, they never ask for ID when you are checking in at a restaurant.
