I've been playing on the latest version with Realms, and I'd noticed a lot of double clicking going on when I interact with things. Laying down two torches at a time, opening and closing a door with the same button push, things like that. I thought it must be the trigger on my controller being weird.

Today I was placing half slabs and it kept laying down two to make a complete block even when tapping as quick as I could. I even moved the crosshair to the side of the block so that after the first block is placed the crosshair is on the side of it, not on top, and it would still stack slabs at random.

I tried to post a video clip of it on XBox, but captures wont show up in the hub for the new Minecraft client.