Here's how the double-move variants in ChessV currently work. (I don't think other variants have specified how 50-move and draw-by-repetition should work.)
Any position can be a repetition, including the first move of two, but will only match positions with the same move status. So the first move of two will only match another position with the first move out of two (and same castling, en passant privs.)
For the 50-move rule, every individual move counts. So a two-move turn could add two to the count. (Internally, ChessV is built for individual moves. The double-moves are accomplished by altering when the side-to-move flips.) I'm not sure how hard this would be to change.
I also think, in general, that repetitions and 50-move draws aren't likely to happen in double-move variants. Even with the one capture per turn limit, the game should still be pretty violent.
Here's how the double-move variants in ChessV currently work. (I don't think other variants have specified how 50-move and draw-by-repetition should work.)
Any position can be a repetition, including the first move of two, but will only match positions with the same move status. So the first move of two will only match another position with the first move out of two (and same castling, en passant privs.)
For the 50-move rule, every individual move counts. So a two-move turn could add two to the count. (Internally, ChessV is built for individual moves. The double-moves are accomplished by altering when the side-to-move flips.) I'm not sure how hard this would be to change.
I also think, in general, that repetitions and 50-move draws aren't likely to happen in double-move variants. Even with the one capture per turn limit, the game should still be pretty violent.