Digit
when most people think of the ice age they imagine that the world was covered in ice for its whole 60,000+ years
you need to look into Interstadials and Dansgaard/Oescher Events to work out what was really going on
these both caused periods where the ice retreated and where migration through usually ice blocked corridoors became possible again
then there would be another stadial or Heinrich Event and the ice came back blocking off the route and trapping anyone who had taken it
this leaves people very isolated in the new lands
and isolated people don't usually make it do they
so the fact that they might well have been in both areas as you speculated is highly probable
but as there were so few hwo made it none of who developed a civilisation we'll never find any evidence
as such the fact that there was anyone there at all is meaningless really
because nothing came of it
