Check this other recent thread www.elitefourum.com/t/weird-seal-on-japanese-gym-2-box-explained/30186/1
Potentially a factory resealed box that was opened to apply 300 yen stickers to the packs due a tax increase in 1997.
However, I’d advise caution. This is not a confirmed and or a widely known practise. It could be a malicious reseal with the intent to deceive.