Hi @Alex_Mondol ,
[I would assume you've meant there are 2 separate clusters, one per site (overall 4 gateways).]
I don't think there is an implementation that we consider as a mistake here.
However, take into consideration that PDP is the one which perform the database operations (communication with IDC, perform group fetch by LDAP, Access roles matching with SmartDashboard configuration) - if both cluster gateways will be configured as PDP, this operation will be done twice.
The other option is to have only one PDP gateway (one of the cluster gateways) and use Identity Sharing between sites.
If we are handling a small scale environment (user-wise) - although this is the more resource efficient implementation, I would recommend take the first one (each site configure PDP gateway), to simplify the implementation.
Group manager, Identity Awareness R&D