Like Jonas said, that's a PAL copy and graded by a company called UKG. Not reputable here in the US, unsure of how reputable they are in the UK and Europe.
In PAL collecting circles, new doesn't mean original factory sealed (which is the way works here in the States) since most PAL releases never came sealed with plastic.
New in PAL regions just means (for the most part) "Never Used" or "Extremely Mint" which I guess they determine by looking at the pins of the cartridge or whatever. Not sure how it really works there really, all I know is they've got some really fun obscure stuff that I like to collect.
Regardless, a US release of Zelda must be sealed in plastic with a proper H-Seam or else it's without a shadow of a doubt, a resealed game. Even if it's been in your hands for over 20 years, it just means when you bought it all those years ago it was opened and repackaged at one point along the way.
Still, if you feel that's not a fair assessment then you can always have it professionally graded. Maybe you have an undocumented no H-Seam variant and it's something unique.
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Got any of these for sale? Sell them to me. I also buy other NES Publisher inserts, and even GB/GBC, and SNES inserts too.