I noticed 2 dupe bugs, and one breaking bug.
DUPE#1: Making a piston pushing a rail downwards that is on top of a block, with no block below it, drops a rail of the same type, but does not break the rail.
DUPE#2: Pushing a rail and a block into the same block at the same time, drops two rails, one for being pushed over air(the block is still a entity, I guess) and one for being pushed up, maybe? I had one piston pushing the rail horizontally, and block going up vertically.
Breaking glitch: when doing the above glitch, the two surrounding regular rails were broken and dropped as normal.
ALSO: When a piston couldn't push a block because obsidian was in the way, and I cleared a block, the piston didn't fire until a block update.