If may happen that the product pages shows two galleries. In this case first check that you have no other product gallery plugin installed/activated. If not try adding this custom css rule:

.gallery-svi.avada-product-gallery:nth-of-type(2) {
display: none!important;
}

Probably the AVADA builder is injecting it twice the gallery one for mobile and another for desktop and for that reason it shows 2 galleries.

Cheers