As the documentation states glassfish has 12 port for different purposes: http://docs.oracle.com/cd/E26576_01/doc.312/e24939/release-notes.htm#ggpoq
The problem is, that you are changing only the http port, but an other port clashes with your second embedded glassfish job.
You are also using an extremely outdated version of the arquillian.xml (dating 4 years back or so..)
See the examples here;
Try setting bindHttpPort as a property on the container/configuration element.
(LOL in retrospect this was an _extremely_ old forum post as well.. oh well)