Defiant

When Commander William Riker from the Enterprise visits the station, an intrigued Kira takes him on a tour, particularly of the Defiant. On the bridge of the docked ship, Kira uses her access code in order to show him more of the Deflant's operations. But Riker suddenly stuns Kira with a phaser, and with the help of two comrades, Riker fakes an emergency on the warship and convinces Sisko to have it freed from the dock. The Defiant engages warp drive and leaves the sector, at which point it is revealed that the man stealing the vessel is actually Thomas Riker, Wil Riker's duplicate, created as the result of a freak transporter accident nine years ago.