Steps to reproduce
Place a chest
Diagonal to the first chest, place another chest that is facing the same way.
Use a piston to push the second chest next to the first chest.
Place another chest on the other side of the first chest.
Expected result
After step (3) you have two single chests next to each other. In step (4) you create a double chest.
Observed result
After step (3) you have a double chest. In step (4) the double chest disappears and you visually create a new double chest, but you actually have three linked chests. The game may crash if you interact with the chests or try to place another chest next to them.
Pistons can create double chests by pushing them together in the latest preview, but in doing so it allows you to create triple and quadruple chests by placing additonal chests down adjacent to the sides of the double chest. Interacting with these chests has some weird interactions and can even crash the game. This does not happen in the latest release of Bedrock edition, as double chests are not created when chests are pushed by pistons.
I apologize for the poor framerate in the video.
In addition, combining two chests with a piston or breaking a double chest with a piston where one of the chests is receiving items from a hopper creates “ghost items” where the hopper is placing items into the chest, but visually they disappear if you close and open the chest again. Comparators stop interacting with the double chest as well.
I can reproduce this by creating a 3x3 “piston feed tape” of chests. Where 1/4 pistons is controlled by a comparator.