I was going to reserve a hotel room for two nights. Do I only pay the $50 deposit once for the two nights or would it be $100 for the two nights?

How much is rooms

If you use credit or debit card, they will charge then reverse when you checkout. 1 time deposit per visit.

Once

The last time I stayed the deposit was for 1 night

Actually they say 50 dollars to reserve a room however it's 60 but when you leave your money goes back to your card but it could take up to a month.

One deposit.

Usually per stay.

Depending the hotel ...be prepared to pay deposit per night..