Tina Kong of Nanaimo, B.C., and Kevin Sam Bath Ses of Calgary were both 21 when they were gunned down at the restaurant in the city's northeast in October 2008.
Two men were injured, but recovered.
Police say pictures from a nearby convenience store camera around the time of the shooting show two people who may have information about what happened.
The shooting is believed to be related to a long-standing grievance between two street gangs responsible for several high-profile acts of violence since 2005.
Anyone who may have information about the men in the photos is asked to contact police.