Star Trek: The Motion Picture--Echoes

"When a space anomaly thrusts a bounty hunter and her target--a criminal mastermind--into their universe, it's up to Kirk and his crew to stop them from unintentionally starting a war with the Romulans and unleashing a superweapon of foreign tech onto the system. But the strangers from another universe are more familiar than they assume...for underneath their helmets are their doppelägngers--from an alternate reality!"--