Then, in 1970, the GTO had a redesign that similarly changed the grille from a a grille that stretched the width of the car in 1969 (and had concealed headlights in the grille) to the dual grille design, as seen below. The GTO made the dual grille design famous for Pontiac and it became a symbol of the brand.
This was by no means an attempt to copy BMW - it was just an evolution of the prior grille designs.
While imitation may be the highest form of flattery, BMW didn't think so. I heard that when the Grand Prix was redesigned for 1997, BMW sued GM over the use of the dual grille design on the car. A little ridiculous, me thinks.