Is there a way to make a perfect body double?

Say someone was playing 5e and walking through a forest, and wanted to plan an ambush. Could that player, say they were a Dragonborn wizard, potentially make a "body double" of themselves, and then polymorph into someone, or something, else to wait in secrecy?

For Instance:

Dragonborn polymorphs into a deer, waits in forest appearing to eat grass as a deer would, goblin team walks down the road, notices the "dead body" in the middle of the road. Goblin party begins to loot dead body, Polymorph ends, FIREBALL!!! No more Goblin Party…

Depending on the answers to this question I will have another!