User blog comment:Mcpegamer9000/ANYONE KNOW A CHEST DUPE GLITCH/@comment-12413098-20130903090744/@comment-12413098-20130903090911

Or there's block duplication:

Place the blocks.

Go to home menu.

Double tap home button and erase MCPE from the hotbar.

Go onto MCPE. The blocks should be on the ground and in your inventory.