Phpmyadmin says, that there are two identical indexes in the virtuemart product_price table. The first is for the virtuemart_product_id key name, the second for the product_price key name. And one of these indexes can be deleted...
My question is- which one and what is reponsible for this double index?
virtuemart_product_id is in any case very important and correct, but you should use vm3.0.13.2 and the enhanced tableupdater.