Two For One Deal Achievement in Resident Evil 3

One of the easiest way to get this one early on is with the shotgun, and on the baby spiders at the Subway Power Substation. Just have them group together then unload on them. You must kill them with one shot though. Another easy method will be on your way to the Power Substation, to your right will be a fence with zombies lined up. With the shotgun, have the ones at the far end lined up then fire.