noun
holding two positions at once (sumo)
Sumo term for a person who simultaneously holds two official roles, typically a rikishi or judge who is also a coach. The phrase literally means 'two licenses'.
彼は現役力士でありながら、二枚鑑札で部屋のコーチも務めている。
While still an active rikishi, he also serves as a coach at the stable, holding two positions at once.
Compound of 二枚 (two sheets) and 鑑札 (license, permit), referring to holding two licenses simultaneously. The exact historical origin in sumo is uncertain.