Bearing in mind the fairly common practice of people using their second names rather than their first (in Wales at least), these might also be worthy of consideration:
Malbork Poland Stalag xx-B:
C D Roberts, RASC, Army no 108679, PoW no 14524
R D Roberts, Royal Warwickshires, Army no 5952130, PoW no 9073
D Owen-Roberts, Welsh Guards, Army no 2734727, PoW no 7640
J D J Roberts, The Buffs, Army no 6289682, PoW no 6685
Regards
GS