You need to place each application in it's own class loader space
This can be done with the jboss-app.xml in the META-INF directory of your ear
seam.jboss.org:loader=<your unique identifier>
Thanks very much! This was exactly my problem!
In case you are wondering about it failing on the 3rd deployment instead of the 2nd... it turns out I had given the 2nd app a different identifier already, but the 3rd was a duplicate of the 1st, and I was always deploying in the same order. I was wondering why it wasn't failing on the 2nd deployment. Thanks so much for your help!
Previously we had jboss-seam.jar and jboss-seam-ui.jar in the jboss deploy directory. With the upgrade we've changed to the new structure where these jar's are packaged into the ear file.
jboss-seam-ui.jar should go in WEB-INF/lib.