================= Do you think it is a good idea to run 2 jboss servers pointing to the same database?
One jboss would have one ear file, and the other one would have a newer version of ear file.
Yes, you can have 2 JBoss servers pointing to the same database without any problems. If both servers are in same mechine then the only needed precaution is maintaining different port numbers for different servers.
In one of my project, I am supposed to run some batch jobs containing huge database round trips. I distributed my work by installing 3 JBoss servers with different port numbers in 4 different terminals. The database is same for all of those. So, totally 12 systems worked without any problems.
Same logic you can use with different .ear files also