Are Hella rear bulb holders sided?

[Cazz]

Hi all, I'm in the process of preparing the rear lights to go back on my camper. I originally had one Hella and one ULO, I'm changing the ULO for Hella.

The problem is I seem to have 2 near side bulb holders, only one fits. Can any one tell me please, if I turn one upside down, swap a couple of bulbs round and trim that plastic bit off, will it fit and work? Or is that plastic bit there to stop me getting it back to front?
I notice the ULO bulb holder is universal, I'm not sure how the Hella differ. Thanks in advance for any help.

[Aidan]

yes they are handed there's a pin and hole arrangement so they can't be swapped around which is a pain when you want to fit fog light to lhd imports

[Cazz]

Thanks for that, I'll put a wanted in the wanted. Why didn't they make them universal, like the ULO one.

I wonder what the actual difference is, apart from the pin and hole.