1.Each DAG can have 16 Mailbox Database as its Member
2.Each Database can have 15 Copies replicated
3.You can have Multiple DAG in the Exchange Organization
4.Each Server can be member of only One DAG
5.Its not possible to have multiple coplies of the same database in a Single Server
6.if you have multiple Database copy only one database will be active and will server the users and all the other copies of the Database will be Passive
7.You can have same database Active in Multiple Exchange servers, but still only one Database will server the purpose