OK, Scirocco should be fixed now. It seems all captures must have an ep property, even if it is set to false, and non-captures should never have it. The moves induced by the Dervish now conform to that, and indeed the problem in the given position went away.
I did not change anything in the moves induced by the Harpy; these are Knight moves, and I already exclude induction on pieces that have Knight moves. (These are easy to recognize by their ID.) So the induced moves can never be duplicats, as pieces either have all Knight moves, or none at all.
OK, Scirocco should be fixed now. It seems all captures must have an ep property, even if it is set to false, and non-captures should never have it. The moves induced by the Dervish now conform to that, and indeed the problem in the given position went away.
I did not change anything in the moves induced by the Harpy; these are Knight moves, and I already exclude induction on pieces that have Knight moves. (These are easy to recognize by their ID.) So the induced moves can never be duplicats, as pieces either have all Knight moves, or none at all.
I pushed the fix.