There's no reason I can think of why you couldn't have a binary planet...
that is to say, two planets of approximatly the same size, orbiting the same center of gravity in an earth like orbit. (Just make the Earth's moon larger and move change the orbit slightly and you could have two similair worlds sharing the same orbit around the Sun.
Or you could have a jovian or super jovian in an earth orbit with several earth sized "moons".
Anything is possible (In the mind of a non-space expert/accountant!)
Scott