You can submit 2 games if you want to, if you work on 2 games during the month then that's fine
Viewing post in Multiple Submissions?
What about submitting three games? I already submitted one game to the Jam and I'm very close to finish two more. I'm working on bugs that I haven't had time to fix in months because I was busy with my teaching job. The three games are related; I was originally planning to use them as levels of a bigger-game but I ended up splitting the project in three games.