Two ES in One PCS7 Project

Hello everybody,

My question is about considering two ES in one PCS7 project (not in multi-project). Is it possible to have two ES connected to plant bus and also terminal bus with two different IP address? In that case, if it is necessary to install ES/OS single station on each station with different license or one license can be installed on both station? Also how I can transfer any data change from one ES to another ES? is transferring data possible with selecting relevant station and download command?

thanks in advance