Can an EJB bean implement multiple user defined interfaces, except business interfaces (@Local, @Remote) or No-Interface view (@LocalBean)?
For example define two in
The given example is illegal, but nevertheless accepted by quite some implementations (application servers).
David Blevins started a thread about this on the EJB mailing list a while ago.
EJB 3.2 will make the rules more clear for this topic. See What's new in EJB 3.2 ? - Java EE 7 chugging along! (look for section Simplified the rules to define all local/remote views of the bean)