Bump. I just finished organizing my entire collection (still have to put them back into the binders).
Does anyone know the difference between let’s say a Pokémon Song Best Collection CD Cool Porygon and Nintendo 64 Cool Porygon? They are graded separately by PSA, how do they know the difference between the two? Is there any difference?
Same question for the other CD Promo cards:
- Venusaur/Charizard/Blastoise: CD Promo (Jan, 1999) vs Trade Please campaign (Feb. 1998)
- Arcanine: CD Promo (Jan, 1999) vs Toyota campaign (Oct. 1997)
- Mew/Mewtwo: CD Promo (Jan, 1999) vs World Hobby Fair Special Sheet / Vending Machine Series 00 (Dec. 1997)
- Hungry Snorlax/Cool Porygon: CD Promo (Jan, 1999) vs Nintendo 64 campaign (Dec. 1997)
- Computer Error: CD Promo (Jan, 1999) vs January 1998 CoroCoro Comic (Dec. 1997)
- Super Energy Retrieval: CD Promo (Jan, 1999) vs Pocket Monster Fan Book (Apr. 1997)
For the Pikachu I know the difference. 
The CD Promo is printed on Japanese card stock, and the English Shadowless Base Set yellow cheeks Pikachu on English card stock. But is that the only one with a difference, and all the other Glossy Japanese ones are just exact copies of their earlier releases?
I read in this post by @nine about the non-Glossy Super Energy Retrieval variant (with different text) that the Glossy version of the Super Energy Retrieval from the CD Promo and Fan Club are exactly the same. As @pkmnflyingmaster states as a joke, PSA uses a coin flip to determine which of the two labels to use. I guess this applies to all of the Japanese Glossy promos that were part of the Pokémon Song Best Collection CD in that case?
Greetz,
Quuador