They Were 11(1986)

11-nin Iru!

In the distant future, ten space cadets embark on a survival test that sets them adrift in a derelict spacecraft from which they must find their way home. Terror strikes when the cadets discover eleven of themselves aboard the ship. Who is the imposter, and what is his (or her) purpose? Paranoia runs rampant and lives hang in the balance as the cadets scrutinize one another for any wrong move. Can they identify the spy before it’s too late?

(Source: Central Park Media)