Because booster packs are randomized during production, duplicates may appear and completing a full set is not guaranteed from a single box
Another hot area is the Unova revival with Black Bolt and White Flare dual sets, where monochrome BWR rarities are flying off shelves
Put two of them onto the battlefield tapped and the other into your hand, then shuffle
As to the one with the chubby Charizard, that might be the cover of one of the Trainers Pokemon TCG magazines published in Japan, though Im not sure of the issue and a cursory google image search doesnt bring it up
Incapsula incident ID: 568000120651161022-74938400439272232
On the other hand, it's very possible that newer players could be fooled, especially when it comes to older cards that occasionally feel weird even if they are real, thanks to variance in the printing process, or things like Masterpieces that have a strange foiling process