What's the point?
Wouldn't the point be to increase the number of "holes" (and, thereby, multiply the number of "courses") that could be played on any given property?
Put aside the liability issues, and imagine a small, private club with limited play and air-tight waivers. Wouldn't it be the height of fun to play (and an extraordinary challenge for an architect to design) holes with double greens where, one day, you'd be playing to all RIGHT pins; the next to all LEFT pins; the next to RIGHT, RIGHT, LEFT, LEFT, RIGHT, RIGHT, LEFT, LEFT (etc.); the next to LEFT, LEFT, RIGHT, RIGHT, LEFT, LEFT, RIGHT, RIGHT (etc.); the next to some other configuration?
I agree that, from what I've seen of them, double greens are just plain gimmicky (except at the Old Course, of course!) if you always play to the same side of every double green going out and every double green coming back.
But if you could vary the rotation ...
(PS: Started this an hour ago. Just finished it -- and see that Mr. Schmidt beat me to the punch! I think. Well, as they say, great minds ...
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