i lost my fairly obtained key
https://xcraft.ru/battle/index.php?battle_id=bda8fb6b07feb8f8d22dd47e844095de
and tried to get it back, but without success
https://xcraft.ru/battle/index.php?battle_id=b63a19df7d133542a96eba246f0c99a8

Is it a bug or is it okey?

You can only obtain a key from a player who has more points than you. Him being able to take your key pretty much guarantees that you can't get it back unless you drop your ranking.