Back when I was learning about how to craft magic items in 3.5, I was told by the GM that in order to get around enhancement bonuses not stacking, you could make an item with a "misc" bonus, or an "unnamed" bonus, as these do stack.
He explained that you could make an item that normally has an enhancement bonus (say, Cloak of Charisma +2 enhancement) have a misc/unamed bonus instead by paying double the cost. So you could wear more than one stat increasing item for the same stat.
However, I have been unable to find this rule anywhere in the books. Was this a houserule and the GM gave me the wrong impression?
Can you pay double to craft an item that would normally give an enhancement bonus to instead give an unnamed bonus? And if so, where is this in the rules?