I have read that some experts have run two brushless motors from one esc, but mere mortals had better use an esc for each motor.
Go to
http://www.ezonemag.com/ , click on Discussion and do a search for "twin esc" without the quotes.
One modeler warns: "Some report good results, some dont! The motors must be as close as possable to design spec. Even variations between production motors will cause problems." Other problems are balky startup of motors and one motor shutting down if they are wired in parallel.