(Michigan thoughts).... Legally, it's the landowner's deer. He shot it dead on his own private property. Even if the landowner lied and fired another shot into an already dead deer, the pair of hunters have no bargaining rights. Owner has the right to chase them off his property, provided Private Property / Keep Out signs are posted.
Any "tracking-retrieval" agreement with landowner by original pair of shooters, has to OK'd by the landowner.