There's nothing prohibiting the developement of multiple sapient creatures, but once they discover each other there will be trouble.It's possible, if it was a large planet, with as many as 5 continents(remember one species is aquatic) that were seperated long enough, it's plausable that a multi-species planet developed.
Look at things like the crusades, started over something as trivial a persons beliefs.
Then there was the conquest of Africa and South America, where anyone that wasn't white was deemed inferior. And these were members of the same species! Could you imagine the response if Colombus had been greeted by a talking insect?
It is unlikely, to say the least, that more than one or two of these races would ever survive to develope space travel.