EASY....
You are I hope using a cover with your 'duvet'?
Well now you will need 2.
You put a very plain one on first, then the one you normally would cover it with.Sure a little extra work...but what's 2 mins extra.Make sure the first plain one is cotton 100% so it can breath.Very cheap to buy at say K-Mart.
You will also find, it give's the 'duvet' that 'Magazine Look', because it keeps it all fluffed up, and looks and feels great!
If you have not ever used a cover, you really should.At night we sweat, and it will keep your 'duvet', from smelling in time of your perspiration.
But because of the feather's 2 cover's are sometimes needed...Don't worrie they still give amazing snuggle time and keep you warm.