Ctrl+pick block creates an exact copy of the block at hand, including NBT data and tile entities. However, I have discovered that the block will lose its NBT data if placed inside another container.

How To:
Ctrl+pick block a chest with items inside of it. Take this chest (Chest 1) and store it inside another chest or an ender chest (Chest 2). Close chest 2. Reopen chest 2 and take chest 1 out of it. Place chest 1 down and open it. It will be empty. All the items will be lost.