matching dice; doublets
In dice games, a roll where both dice show the same number.
If you roll matching dice, you can roll again.
bet on two horses in the same bracket
In Japanese horse racing, a bet covering two horses that are in the same bracket (枠).
repdigit; monodigit
Mathematics term for a number consisting of repeated identical digits, like 11 or 222.
In horse racing, if you bet on two horses in the same bracket and they come in, you win.
Numbers like 111 or 222 are called repdigits in mathematics.
Most common spelling; katakana ゾロ plus kanji 目.
Hiragana variant; less common but still seen.
ゾロ (zoro) is an onomatopoeic or mimetic word suggesting things being the same or lined up, combined with 目 (me, 'eye' or 'pip' on dice). The exact origin is uncertain.