I'm sure there are many courses that open with two very short par-4's, but I can't think of another top-100 level course that does, off the top of my head, and certainly not as short as the two at National.
One interesting fact is that when National opened, the starting point was at the 9th green, near Shinnecock Hills, and these two holes were at the turn. I presume Macdonald always envisioned the grand clubhouse overlooking the bay, but I have never read anything about that, and I wonder whether he always envisioned these two holes would be the starting holes.