Ok, this was a huge deal in AX 2009 in my opinion. During the TAP program of AX 2012, a whitepaper was released on how to do this, but we've had to wait until now for Microsoft to make it public.
So, yes, it is now possible to have several instances of SQL Reporting running on the same box, connecting to different AOSes. Note that you do need a separate instance of SQL reporting (not one instance connecting to different AOSes), but even that was not possible with AX 2009.
You can find the information on technet at http://technet.microsoft.com/en-us/library/hh389760.aspx.
(Source: EMEADaxSupport blog)