Villiers MK 6 rebuild

Hi

i know I’m lazzy and should search the site or research it but it’s such a quick question and probably an even quicker answer. I’m rebuilding the engine and the two half’s of the crankcase have left and right stamped on them. As far as I can see they’re identical but there must be a difference otherwise why mark them. So is there a difference and if so how do I determine which side of the engine To face to know it’s left or right position. Thanks