Yeah they are them, but that doesn't necessarily mean they're dead. I mean if you think about it those "ghosts" only appear in Home World, not in the other dimension. So if they are dead they only died after 1010 AD. And it doesn't make sense for them to be little kid ghosts since by then they'd be almost in their 30's. I think the next game will say for sure what happened to them, but I mean for all we know they could just be holograms put up to guide Serge to the right path. I mean, there's lots of answers.