Nope - haven't seen one. Why not replace them with something in an iron you can see. Most double rifles have centre ribs.

Centre ribs can be dovetailed to allow inletting sights.

There are many different 'express sights' out there, some quite reasonable in price, that can be mounted in the rib.
I don't see a problem as I have never been shy about changing sights I didn't like. Being handy with your hands and a few tools is all that's necessary. I just take for granted that all men have minor skills. My fault -
sorry - I do know people who can barely sight in a scope by themselves and run to someone else to mount it for them.