Based on the information you have provided, I would guess that you did something wrong. If you fix it, it should work. ;-)
But seriously, look at the console log for the second instance and post any exceptions that were shown. If there were no exceptions, post the contents of the console output, starting with the run command you entered and ending with the "Started in xxx seconds" message.
Also, post the jboss-service.xml changes you made for each instance. (Remember to enclose your XML text in UBBCode "code" tags - you can do this by selecting the XML text and clicking the Code button above the editor window. Also, click the Preview button to ensure that the formatting is correct and the XML text shows up before posting.)
Finally, you are trying to run two different configurations, and not run the same config twice, right?
It had to do with ActiveMQ and its datasource. Essentially, I had to point the second one to a different datasource. Thanks!