Were you looking for the Halo 2 Vista achievement of the same name?

The Double Kill medal is awarded for killing two opponents within four seconds of each other in standard Multiplayer games and within less time in campaign and Firefight. In Halo 4 multiplayer and Spartan Ops the kills need only be within 4.5 seconds of each other.

The medal was originally represented by two blue stars in a yellow circle. In Halo 4 it is represented by two white stars on a navy blue circle, rimmed with blue and brown. When someone attains and achieves this medal, the announcer will shout "Double Kill!" to the player as the "Double Kill!" medal appears in their HUD. In Halo: Combat Evolved due to a lack of visual medals however, the words "Double Kill!" will appear in the upper right corner of the screen.

Trivia

• The medal has a Bungie difficulty rating of 5 out of 10.
• Earning this medal in a Halo 2 Vista matchmade game unlocks the Double Kill achievement.
• Earning this medal with a single Spartan Laser shot in a Halo 3 free-for-all ranked playlist unlocks the Two for One achievement.
• Earning this medal twice in a Halo 3 matchmade game on a Legendary Map unlocks the Double Double achievement.
• Earning a double kill with the shotgun in Halo: Reach multiplayer matchmaking unlocks the Both Barrels achievement.
• Earning a double kill from the grave in Halo: Reach multiplayer matchmaking unlocks the Totally Worth It achievement.

Gallery

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  The Halo 3 version.

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  The Halo: Reach version.