I was just asked in a text what is wrong with two O-rings, and I thought I would post it here.
when you put two O-rings next to each other, you have a static volume. As Temperature rises, the pressure between the two O-rings will increase. If the shock got too hot both O-rings would fail leaving you with no seal. It is more likely to blow an O-ring when you have two then if you have one. If they really wanted to lips they should’ve used a quad ring.
I cannot tell from your photo if that is aluminum or steel. If it is steel I would be tempted to weld the stud back in with a tig. Let the pressure out of the shock and go slow and cool it often. Otherwise shocks can go boom when welded on.
Depending on the brand of a shock he might be able to get a whole new top cap and replace it.