Both are very rare, but the one on the left is probably slightly rarer and also one I’m still missing in my Pikachu collection. We know the one on the right was limited to just 2000 copies back in 1998. And there isn’t much known yet about the one on the left, except that it was used as Pokémon-card example in some old magazines from CoroCoro and alike. It’s plausible it’s a Sample card that wasn’t intended to be released to the public, but it’s also possible it comes from an obscure release we simply don’t know about yet. It wasn’t until early/mid-2020 that the information about the Glossy Keiji Kinebuchi glossy Pikachu came to light to begin with, even though it was 22 years old at that point, so who knows what info might emerge for this other Glossy Keiji Kinebuchi release with shifted artwork over time. 
Greetz,
Quuador