Salute,

currently the GP module does not allow to use multiple input feature with the same value. At least from the math point of view there is no need for this restriction. Though, I didn't go through the whole implementation to see if there is something special about it that would require this restriction. I tested it on some dummy problem (with noisy data) with and without multiple equal inputs and it worked fine and, not surprisingly, even better when using duplicates (more data yeay!).
Any reasons to keep it?