The problem is that the RA creates two connections instead of one for each connection to TIBCO broker.

Have repeated the problem and I can clearly see the issue: (simple example with two MDBs each with maxSession=1 - should be two connections only)

[tomr@aza java]$ netstat -pantu | grep /tibemsd64 | grep "ESTABLISHED" | grep ":7222"
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 192.168.1.106:7222 192.168.1.109:35812 ESTABLISHED 2182/tibemsd64
tcp 0 0 192.168.1.106:7222 192.168.1.109:35822 ESTABLISHED 2182/tibemsd64
tcp 0 0 192.168.1.106:7222 192.168.1.109:35820 ESTABLISHED 2182/tibemsd64
tcp 0 0 192.168.1.106:7222 192.168.1.109:35810 ESTABLISHED 2182/tibemsd64

This is due to the fact that the ManagedConnection creates a Connection and a JMSContext