I'll admit I don't know chapter and verse of holding 2 licences under EASA rules - all I can speak of is my experience...
I hold a CAA PPL and JAR CPL. When I changed my home addess the UK CAA sent me new pages for both in the same envelope - so they seem to be happy for me to hold both.
I believe that there IS a problem concurrently holding 2 licences of the same "rank" from different EASA states. e.g. If you hold a French PPL and want a UK one you have to surrender the French one. (NOTE: I said "believe" - I'm not 100% sure).
OC619