They were NOT exactly the same IIRC.
I did some work at Lucas Car Braking at Pontypool (in 1993/94) when I worked for Lucas Industries, and we did a corporate project on managing variety at the design stage, and the Rover / Honda brakes were one example where the customer exerted great (perhaps too much) pressure to incorporate their preferred features. Things like a undercut vs a sharp edge at the bolt shank to head interface, instead of a larger machined chamfer on the casting, going into the threaded hole.
Different hydraulic seal and dust seal designs (but the same diameter pistons)
Different sized bleed nipples (At the time lucas had 152 different OE bleed nipples across their worldwide plants - all demanded to be a particular size by different customer design teams)
And obviously loads of different pad materials for different models to give a different feel.
They should be interchangeable, but I'd make sure I had a matched pair. either both with a Honda casting or both with a rover casting.
No doubt it was Rover being the cheapskates