Twins can be very close, especially as a kid with no concept of twins or sense to pick out distinctive details.
My father has a twin brother who lives far away, with the most obvious difference between them that my father generally keeps a beard. One night, when my Dad shaved and came to tuck me into bed, he was met with an "Uncle so and so, when did you get here?".
Of course now as an adult, I'd be able to tell them apart no problem, even if they did dress and style the same. I've observed their mannerisms and minor cosmetic marks with a keener eye as an adult. But as a young kid who couldn't even clearly tell his own father from his twin, I find a kid being unable to recognize a chance encounter he wasn't expecting very believable.
Honestly.... I kinda can. This is an extreme and unlikely scenario, but there's a few things that make me think it's not impossible.
A) Trump has publicly promised to back out of NATO. B) Trump is generally very pro-Russia. C) Trump has generally had poor relations with Canada.
If the US backed out of NATO, they'd have a lot of military power sitting idle, and NATO would be significantly weaker, as well as doubly occupied in Ukraine. Russia would certainly be interested in such a thing happening, given the strategic importance of Antarctica, and how much it would take eyes away from them. I also don't doubt for a second that Trump would love to exploit our natural resources, especially oil, and the military importance of the top of the world. Not to mention it'd be an excuse to continue creating expensive military contracts and posturing as tough.
This is of course, mostly fantasy, but Trump is nothing if not unpredictable.