Why, because the one on the rhs, viewed from the back failed it's MOT on that, and a bulb.
That's the one we're looking at, the other side looks ok ish.
I changed them both.
what makes you think they have failed ,,, just asking , not being funny
did you stand the shocks up right before fitting and move them a few times ,, some old shocks like that , it primes them.