So this is a list thread, but be sure to also provide one screenshot that proves the point.
NO GAP (good games)
Windy x Windam
GAP (bad games)
Catch! Touch! Yoshi! / Yoshi Touch & Go
Contra 4 / Contra: Dual Spirits
Kage no Densetsu -The Legend of Kage 2- / The Legend of Kage 2
Windy x Windam

Contra 4 / Contra: Dual Spirits

Kage no Densetsu -The Legend of Kage 2- / The Legend of Kage 2

P.S. Note that most games do not use both screens as a continuous playing area, so they do not have this problem...