how many async socket requests can be going on on the same socket?

When I call BeginSend on a socket, I pass a delegate which will be called (by a different thread) when the data has been sent.

What would happen if I call BeginSend another time while the first has not yet been 'callbacked'?

What is the correct behavior to send data? do BeginSend, and on the callback do EndSend and start another send? Or is it actually wise to have multiple BeginSends working at the same time?

this is the BeginSend page on MSDN which doesn't give an answer to this question: BeginSend msdn