Well, no, the first commandment's wording doesn't suggest there are other real gods, it suggests that people worship other false gods, but shouldn't; thus, put no god before me. There's no room in Abrahamic faith for other gods; it's one of their defining features, the thing that got them into so much trouble with the Romans.
Now, as the faiths spread, you would often see them interact somewhat oddly with local pagan traditions; even in Africa right now, people who are Christian and Muslim often continue with local animal sacrifice traditions and the like.