When an Enderman puts down a spawer, it loses the entity ID.

/summon Enderman ~ ~ ~ {carried:52,carriedData:{EntityId:Enderman}}
This command will spawn an Enderman holding an Enderman spawner in its hands, but when it puts down the spawner, it'll turn into a normal pig spawner. Same goes for chests, furnaces, hoppers, dispenser, etc.

How to recreate:
1: Do '/summon Enderman ~ ~ ~ {carried:52,carriedData:{EntityId:Enderman}}' about 15 times.
2: wait a couple of minutes untill a block is placed.
3: You'll see that a normal pig spawner has been placed, and not the Enderman spawner that he hold in his hands.