I'm in my fifth year and I'm currently the head coach of England as well as a club. I was asked to coach USA Under 23s and I accepted, but I lost my job as England's head coach. Are we limited to two jobs?
You can't manage two nations at the same time just as you can't manage two clubs at the same time. So yes you're limited to two teams but it has to be one national side and one club side.
EDIT: I should say that if you make a new manager you can take the England job back again. That first thing just applies for each manager you have.