If it is SLSB has a SFSB, then yes you will always get the same instance...
If it is truly SFSB1->SFSB2, then there is a bug. What version of JBoss EJB3?
It is in fact SFSB1->SFSB2 (sorry, I had a typo in my earlier post).
I am using the CVS snapshot from 3/17.