Oyster flex sizing same on both sides?

[CookieButter]

I went gray to buy a 126655 that is a few years old, and the watch has an E sized band on both sides. All of the charts that I see when searching show different sizes for each side, so I expected an D/E or E/F combo. It seems to fit fine, but I wanted to get feedback if there is any disadvantage to having the same size — it is my first oyster flex.

Also, I assume that for durability and sanitation reasons, people sometimes swap out leather and rubber straps when buying a used watch. Do people usually swap out oyster flex straps when buying used or keep what is on it? How long do they generally last?