Aside from the obvious, it may be something to do with the position of any wording/logo when fitted so even though they look the same they might actually be subtly different. On the other hand, they may well be identical and the L and R put there for those who need help figured out left and right…
Hold them together, back to back or front to front, if they match, mirror image, then they’re correct and the “L”/“R” is important, if not they’re not!