Ok I can confirm now
You can reproduce this easily by maximizing sublime and then opening a lot of tabs (new if u want) until you get the little button on the right, when you press it it does indeed appears in the other monitor.
NOTE: This will only work if sublime is maximized! if it's not it actually gets it right >.<
Why it happens only the man himself (jps) can answer it
p.s. I use 3 monitors lol