While you can use the on camera flash to fire a remote SB700, can you use the on camera flash to fire TWO remote SB700 units without additional trigger/receivers in play?
Sure, easy as pie, already included. Not using the internal flash however, unnecessary.
Fire one remote flash with the radio trigger.
Put the other (SB-700) into its SU-4 mode, which is an optical slave already included. (SU-4 Manual mode). It will be triggered in sync by the full working power of the first flash. Standard technique.
Works great.
Or, you could put a radio receiver on both flashes.