I would assume double chocolate means chocolate dough and chocolate chips. Double in essence, not in quantity. And 40% is referring to how many chocolate chips are in the dough.
If it's milk chocolate the 40% is likely cacao content of the chocolate, not the percentage by volume in the dough
Only way to know is if OP shows the ingredients. That brand of frozen cookie dough, however, uses dark chocolate chips for the double and milk for the standard, so it's unlikely.
I would assume double chocolate means chocolate dough and chocolate chips. Double in essence, not in quantity. And 40% is referring to how many chocolate chips are in the dough.
If it's milk chocolate the 40% is likely cacao content of the chocolate, not the percentage by volume in the dough
Only way to know is if OP shows the ingredients. That brand of frozen cookie dough, however, uses dark chocolate chips for the double and milk for the standard, so it's unlikely.