OtterDex
Porygon2

Neo RevelationNEO3 12

Porygon2

Rare Holo in Neo Revelation

No price for this printing yet. That is not the same as worthless — the feed simply has no listing for it.

15 printings of Porygon2

They range from $0.13 to $15.26 — a 117× difference for a card with the same name. The set code and collector number printed along the bottom edge are what tell them apart.

Not sure which one you are holding? OtterDex reads the set code and collector number off the card and tells you.