DutchDutch: Take a step back and consider this........... What is the point of keeping a logbook?
It`s main purpose is to provide a legal record of flight experience(s). Why on earth would you ever think that it was relevant for two pilots on the same crew to both be claiming to have performed a landing? This has nothing to do with being a "required crewmember". The same logic is obvious about the logging of Instrument Time as opposed to Time under IFR.
When I used to to Base Training on the aircraft, in a year I may have "supervised" up to 400 landings without ever having actually performed one myself! Do you think that I should have logged these! Of course not!