If youre going to have a 'blizzlike' and a 'fun' server, or any variation between the servers at all, youll want a duplicated mangos, characters, scriptdev2 databases.
Also, be sure to use a seperate config file, set up with these databases and a different port. I use this batch file to run my second test realm'
c:\\mangos\\mangosd.exe -c server2.conf
Dont forget to add the second realm to your realmd database, and forward the ports in the router if any of your testers are outside your LAN
If you want them the same, (IE, any creature you spawn on server 1 appears on server 2, as well as any other changes), youll only need a seperate characters database AFAIK