The corrupted obelisk is the one that duplicates your pawns, but usually it doesn't also give those duplicated pawns the implants of the original as a balancing measure. I've noticed that at least with charge shoulder turrets they are duplicated, and it's very likely this also happens with the other shoulder implants.

Also, on the operations tab, the operations "Install shoulder rocket pod" and "Install shoulder mortar" appear despite not having those implants or any other edge cases involving those implants.