I am having the same issue. Well, I can have all the MDB instances invoke business logic in a POJO singleton or something like that, but that wouldn't be as neat.
(Basically, a bump!)
You can limit the number of MDB instances in the pool to 1 with:
Thanks! Works as a charm. Implemented the POJO singleton solution first, but this method seems to have better performance, and the messages will be processed in the same order I sent them.