Amulet Coin Doubling
 

If you give more than one Pokémon and amulet coin, do your winnings increase accordingly? If not, what the fastest way for earning money?

It won't keep on doubling, you can only have one Amulet Coin be active at a time. Luck Incense also won't double if Amulet Coin is present.

Closed since the question got an answer.