Yes, the position of the shock access plugs changed. However, that change didn’t occur until sometime in the 1971 production year, so depending on your build date, a 1970 trunk pan might be correct for your car.
My ‘71 Challenger with original sheet metal was built in late October and has the 1970 style trunk pan.
I don’t know when the changeover to the new style floor took place but at least for cars built early in the run a 1970 pan is what is needed.