reserve; spare; backup
note; memorandum
duplicate; copy; stub (of a ticket, etc.); receipt
waiting one's turn
領収書の控えをどうぞ。
Here is your copy of the receipt.
控えの選手が呼ばれて、準備を始めた。
The reserve players were called and began to prepare.
大事な書類は必ず控えを取っておくべきです。
You should always keep a copy of important documents.