A pair of interesting puzzles

@Ashura, if you're referring to my position, you cannot remove either checking pawns since the rook can just take it

You don't need both kings in the position, I think you can always replace the king with another piece, which does the duty the king is doing if necessary.

@Patralgan Correct. Good trick! I'm wondering if it exists an 11 piece solution with a legal position...

@Patralgan
oh yeah. That's correct

I had 11 with a legal position, though I exploited the fact that you can't remove a White pawn (Pe5) as else White is in check. Similarly with the Black Ne4. The tenor of solutions has gone in other directions, so I did not post it.

lichess.org/editor/8/8/8/2qrPK2/2rkn3/2nbP3/5P2

Someone said that double check was impossible. Well, look at this 7 pieces checkmate:
lichess.org/editor/8%2F8%2F3R4%2F3k4%2F1P3P2%2F1P3P2%2F8%2F3R4%20b%20KQkq
Actually, double check could be the way to get 12 pieces or more.

@Marcchacador Such a double check using rooks is impossible according to the chess rules. I'd like to know what is the solution to the problem in a position according to the chess rules.