That's because the new coins are dated 1759 - 2019. The original ones were dated 1759 - 2009,and these are the ones that were released in to circulation. The set of 4 are re-released in an attempt for the TM to make money off the back of the Kew garden demand.

Their mentality is "if people can't find the 2009 for their collection, let's go e them a 2019 version...." it worked, they sold thousands of the new releases, where people just wanted A KEW GARDENS COIN to complete the or collection.