二兎を追う者は一兎をも得ず

[nito-wo-oumono-wa-itto-mo-ezu]

If you run after two hares, you will catch neither.

Meaning:

You cannot do two things successfully at the same time.

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兎 (うさぎ) [usagi]: a rabbit, a hare

野うさぎ [nousagi]: a hare