Not only have I seen it, but I've been victim to it as well. I have had HA shoot two rockets in quick succession into the rear of my tank and destroy me. This would happen in beta and has never seemed to been fixed. Anyone been able to recreate this? Is it a bug? Is it lag? I've seen it happen with each faction.
Unless they resupply from a sundy sitting right there - double rockets are only a visual glitch only and you only get hit by the effects of just the one.