Legally, the content belongs to you, not to an account nickname. Itch doesn't actively check whether the content already exists. It trusts you not to upload illegal content and takes action if someone reports it.

You shouldn't have any problems, but it's best to contact support with all the information.

It will be a problem if you have two live duplicate accounts with the same games.  It will look like something dodgy is going on. 

As hechelion said, it's best to ask support if they can help you recover the account, or remove it, so you can republish the games.