The gates of Dragonstone have two doors (GoT Season 7 Episode 1).
Why? Wouldn't a gate be stronger if it had a single door, even if it were to open inwards (harder to ram open using the principle of moments, since aiming a battering ram at the edge would now be much harder).
The only reasons I could think of is that for the same width, a single wide door would: (a) have a weaker core (more of it is just wood, not reinforced), (b) have more distance between the outer edge and the hinge, requiring less force to open and (c) during peacetime you could do some flow control and traffic management with a double door, by closing only one.
On the other hand, having a wide open maw in the middle (see picture below) probably makes this very easy to ram down the middle.
Note: this is different from the related question "Why do castle gates in GoT open inwards?"
Authors frequently delve into all kinds of engineering depth while worldbuilding; has any discussion about this come up in the books, fan interviews... to be clear, I'm not asking why this was the case historically, just in this particular realm.