Busse TGLB is my only double, had I unlimited funds the number would be much higher. This one is my favorite knife design I have ever seen.
I did buy 2 Benchmade mini Infidels, one is in my safe as I carry a full size Infidel, the other I gave to my wife.
There are others that I feel like obtaining doubles for,
Swamp Rat Rodent Solution, this one is my EDC fixed and I would like a back-up. Great design for a hunting knife.
Benchmade 51 Morpho, pretty much a perfect Bali-Song in every way.
Benchmade 610 Ruckus, discontinued but it is my favorite large folder design ever, and an extra would be great to have JIC I ever loose break my only one.
Busse Magnum Bear Cub, I own zero and never have, but I plan to eventually buy two of these.
Benchmade 808, another great large folder, want a 2nd before they are discontinued.