Can I run two 2500watt 240 volts heater s in two separate rooms with two thermostats on the some 30 amp breaker

Yes, as long as you have #10 copper wire. The two heaters combined would draw aprox. 21 amps. Do not try to use any lighter (higher gauge) wire.

This all depends on how many watts your heater draws. They should be labeled. Now you need to convert Watts to Amps. Watts divided by Volts equals Amps. (wish I new how to find simple math symbols on this complex computer). As an example 12 Watts/ 12 Volts = 1 Amp. Therefore if you have 120 volts at 30 amps you max is 3,600 watts. If everything is done correctly (proper wire size et. al.) I wouldn't go over 80% of that to be safe.