You can’t double deposit. There is a whole thread going about this right now.
It might help to be clear. YOu posted this in the USC forum. Did USC admit you for Spring? You got off the waitlist for another school with a May 1 deadline. So you want to deposit at College X AND say yes to USC at the same time. I guess without the financial aspect of USC not returning your deposit, you could choose to do that, but let’s face it, you can’t deposit at and attend College X and also attend USC in the Spring.
What does the agreement for USC say? Does it say you will not deposit anywhere else? Does it hold you to some kind of promise? You said it’s a statement, and I am guessing that it’s some kind of statement that you agree to begin in the Spring.
You mention whether courses are online or not in the fall. Frankly, it doesn’t matter. College starts in the fall. It is not the problem of the college if you decide you ONLY want to begin college if and when it is taking place on campus. Effectively, you want to secure your spot and hold out hope that you will be admitted for USC’s fall admission, correct? At which point you would then deposit at USC, and lose your deposit to College X. Or do you prefer College X?
Anyway, I don’t think anyone can stop you from doing this, but I doubt it’s ethical. We need to know what the May 1 statement for USC says.