They try to in the US but not here in the UK.Most US winders get around it by supplying the p/up with a cover that can be removed by the user yielding, surprise,surprise a double cream.The whole patent thing is a bit of a farce especially when it relates to colour as there are so many variants.
To be honest Gibson had the first double creams so it should be them that get funny about it but Dimarzio have this funny way of thinking they've invented everything and wacking patents on them.