Paxton58,
Are you talking about multiple throttles on a machine running JMRI? JMRI can have as many Throttle windows as you want! I've had more than 50 on the screen at one time.
Or are you talking about a mobile device running EngineDriver or WiThrottle? That is beyond my knowledge, and will leave that to those who have direct knowledge.
Regards,
Billybob