Toilet tank bolts with only one nut?

Hello

Have you Ever seen a toilet tank with only one nut holding the tank on each side so that’s really two nuts

instead Of the nut directly under the tank there’s a washer that extends through the hole instead of the simple washer. So the nut that holds the tank to the bowl is also applying the pressure to the tank washer.

Usually there’s one nut directly under the tank and all it does is apply pressure to the washer. Then the bolt extends into and thru the bowl where the second nut holds the tank to the bowl.

I noticed this when I tighten the screw because of the leaking tank. Which stopped the leak. I am wondering if I should just replace Bolts and washers. With a more standard washer. Not even sure I could buy that washer they have in there that extends through the whole