How to move replication data from one DD_01 to DD02

Hi All

I have avamar replication system with single DD, it has 2 differences exp dates (4 years & 7 years) on data domain. I will add 2nd DD. My questions:

1) how can I check how much data on replication data exp date (4 years)

2) how can I move replication date (exp date 4 years) to new DD ? 

Thank you.