I am pretty sure it is *not* allowed. One account per person, regardless of if you deposited or not.
I have seen rakeback sites mention that you can do this. I think it's breakin the site rules, but I think it's a largely unenforced rule. That is, the
poker sites don't keep records of free games, and if you never made a deposit they might not have your information on file.
I don't remember what info I gave on PS when I signed up for my original account, but I know on FT if I look my info up, it's blank. No address, etc. I've never made a deposit on FT.
I asked FT the same question as I wanted to deposit there and take advantage of a rakeback program. But they said that once I had an account, even a non-deposit account, I wasn't allowed to create another. I told them that if I couldn't get rakeback it was a deal breaker and I wouldn't deposit, as I couldn't live with knowing that I could have had 27% of the rake back.
They ended up putting my name on a list. They're experimenting with a rakeback program for current members, and if it gets green lighted I'll be added to it.