My 7 year old DS insists on sleeping with 2 double duvets. He sleeps in a single bed and refuses to get in bed unless he has both of his duvets. It genuinely stresses him out if he doesn't have both double duvets. All through summer we had several bed time arguments about him overheating in the night but I hate seeing him upset so he normally sleeps with both duvets. My other kids just sleep with one single duvet. I normally get hot in the night so I sleep with one duvet, unless it is winter and then I might use two. Is this a normal thing? Or is my son just strange 