@swolepoke is indeed right. It’s from the Pokémon Song Best Collection CD promos. It’s also mentioned in my Base Pikachu variations article. When you shine through both cards with a flashlight you will clearly see the difference, since the Japanese card stock will let a lot more light go through. These two Mewtwo should be the same if it’s indeed printed on the same Japanese card-stock.
PS: Here is a picture of that same Pikachu sheet in full: 
Greetz,
Quuador