Hi Omar,
If you need the sets of components you will copy to be synchronized between your two models (I mean, so that, if you edit them somewhere, they would automatically be updated accordingly in the other models), then I think a good way of doing it would be REC/RPL.
You can see more about REC/RPL in the Capella help contents (Help/Help Contents/Capella Guide/User Manual/Replicable Elements).
Otherwise, maybe this post could also help you: Copy Diagram from a project to an other