Variation quantity not calculate properly

Hi, I try to use variation quantity the same case like your demo here: https://ppom.nmediahosting.com/product/woo-logo/
But not like the demo its multiply twice in the cart.
First its multiply the quntity price with to quantity you choose.
And twice its whole total price with the quantity again.
I used it before in other site and it was okay then.
Thanks.

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