two-bit

Grishamの短編小説Casinoを読んでいます。
“It's over, buddy,” the manager said, then glanced at two thick security guards who had suddenly materialized behind Sidney, who calmly stuck a pretzel in his mouth and crunched it loudly. He grinned at the manager and the pit bosses and decided to call it a night.
“I want cash,” he said.
“That might be a problem,” the manager said.
They escorted Sidney to the manager's office upstairs, where the entire entourage gathered behind a closed door. No one sat down.
“I demand cash,” Sidney said.
“We'll give you a check,” the manager said again.
“You don't have the cash, do you?” Sidney said, taunting. “This two-bit casino doesn't have the cash and cannot cover its exposure.”
“We have the money,” the manager said without conviction. “And we're happy to write a check.”
ギャンブルにはまると普通は文無しになるのですが、そこは小説、主人公のSidneyはカジノを潰せる程のギャンブラーになりました。
さて、bit は小さい、ちっぽけな意味があるのでこの "two-bit" も同じ様な意味だと思いますが、何故 "two" が付いているのか気になります。
・Oxford English Dictionary: Insignificant, cheap, or worthless: some two-bit town
・Cambridge English Dictionary: worth very little, or not very important: He plays a two-bit Chicago gangster in the play.
中々語源に触れている辞書はありません。しかし、Wiktionaryに次の説明を見つけました。
Etymology: based on the old monetary bit, which was one eighth of an old Spanish dollar (or 12½ cents in more modern usage)
two bits pl ‎(plural only): (US, slang) Twenty-five cents, or a quarter.
納得です。