[quote=@Crowvette]
Actually that makes me wonder, is there any way of the PCs knowing there are other returners? I don't know if they'd all have motivations to share it with everyone but it's kind of a needle in a haystack situation if they don't know and don't have a incentive to tell each other
[/quote]

There won't be any external signs or anything. Aside from the fact that most people will know the same version of events (some of you may have been in different places and thus may learn things others didn't), and thus will be able to tell "Wait just a minute here, I don't remember X doing that..." Players may very well end up thinking they're the only ones for a while! 

Which, if you think about it, could make things very interesting. What if one person wants to make sure something happens exactly like it did previously, but another person wants to change it? If their biggest advantage is their foreknowledge of events, then what happens when those events are no longer foolproof? I can't wait to see what happens as you all pursue your own agendas... >:D