I have made multiple submissions. The Agents are going to answer at different times. If more than one answer requests to see the remainder of the work, is it proper to send the stuff to each of them and see which one comes up with a firm publishing offer?
This is a really good question, Personally i would send work to each of them. Even if one shows initial intrest they may not offer you a deal at the end of it. Maximise your chances!