Here there are two unary negative sign operators looking around, as we might say, for operands. Unlike the situation for binary operators where in situations of equal precedence evaluation proceeds from left to right, here, with unary operators of equal precedence evaluation goes from right to left. So, the value of two is accepted by the right most negative sign producing a value of negative two, or the opposite of two. This value is handed over to the left most negative sign producing the negative of negative two, or the opposite of the opposite of two, which is positive two. In this case, then, it is fine to talk about double negatives and say that two negatives produce a positive.
Unary operators have precedence over binary operators.
Resolutions regarding binary operations of equal precedence proceed left to right. Resolutions regarding unary operations of equal precedence proceed right to left.