I have both Kai and Terra Nova Gardenia, and while I've never found a "dupe" of any fragrance, like
I Bought the Terra Nova yrs ago but do not personally find it to be akin to Kai. Kai is...+
A few that come to mind: Pacifica Tunisian Jasmine, Rochas Tocadilly, Ava Luxe White Lilac, +++
As it is my one of my absolute favorite fragrances I can tell you there is no substitute for Tova++
I have TN China Musk & it turns a bit sugary on me, which I don't like (more)
I don't know that one but Kuumba made or terra nova pikake lei is good too if you like kai