If two men ride on a horse, one must ride behind.

两人共骑一马，就要有人坐后面；一山不容二虎。

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As well as flagging names on watch-lists, it also sifts historical records to reveal hidden relationships: if two men have entered a country several times on the same plane, sitting apart from each other, might one be a moneyrunner and the other his overseer?

ECONOMIST: Computing: What's in a name? | The

If the two men were still alive, they had to be found quickly.

FORBES: Murders and Pensions: The Need for Forensic Investigations (March 28, 2006 )

Rivkin says that if the two men came to her for therapy, she'd first listen to their gripes about one another.

CNN: Shame and blame: Why Washington needs couples therapy