-_-
What if they leave Robo in 600A.D., recruit Robo in 1000A.D. and then travel back to 600A.D. and recruit another Robo, then repeat...
Yeah I've thought about this. Let me modify it a bit.
They appear in 600 AD after recruiting Robo and recruit Robo again. This is an analagous case to getting any two items in the Sealed Chests. But what happens if they then go ten minutes in the past and recruit Robo
again. Well, now they would have
three Robo's. But only for ten minutes! Because after ten minutes that third Robo would disappear due to Time Bastard. This isn't a problem with the second Robo, because he would stick around for 400 years before disappearing because of Time Bastard.
So basically, they could recruit as many Robo's as they wanted to, but eventually all of them would have to disappear except for the second one which would stick around for longer than all of their cumulative lifespans.