It could be just another Lapis Lazuli, but we learned in that episode that same Gems don't necessarily have they gemstones located on the same body parts. So the fact that both this Lapis and our Lapis have their gemstones on their back makes them more likely to be the same character, although of course it's not definitive proof and they still could be different Lapises. But I like to think that they weren't, because why not