is khepri even good to use my coins on getting x2 her??
I would say yes, because getting the 5 star tickets will only let you summon from the premium pool which is always available. Those premium childs haven't changed since the start of the game, so there just aren't as many opportunities to get Khepri outside of this event compared to the other available options in the shop.
Unless you're planning on spending real $$ to uncap khepri further, perhaps the 5star tickets will be more value for your coins.Edit: I should have elaborated, my bad. Having a +2 Khepri is not really worth investing into unless you plan on spending some cash to uncap her to at least +4. Even a 4star lvl60 +6Artemis/Morrigan will deal more damage than a lvl60 +2 Khepri with the same gear. The 5star tickets will give you a chance at getting childs that you can actually uncap. Since we're looking at Dark Attackers: Frej & Elizabeth, who are both arguably better units than Khepri, (Frej being *IMO* the best attacker in the game) are from the regular summon pool.TL;DR: If you want to collect the waifu, the quest gives you the only copy you need, so NOT WORTH. If you want to use her competitively, you gotta spend some $$$ then it will be TOTALLY WORTH