Both are changing their duvets from singles to doubles. I've looked at M&S, John Lewis, Debenhams and Dunhelm Mill. Where else could I find non-childish but not too grown up double duvet covers for DC?
Both like stripes, no flowers, pictures, characters, footballs, boats, union flags etc. Main accent colours in DS's room are red & blue and DD's are turquoise/ jade.
DS(9) currently has the JL Robots & Rivets single cover and the M&S blue & red stripy cover, but they don't seem to have them in double. DD(12) has the jade stripy Ikea cover. They do it in double, but she'd like a change. 
Any suggestions please? Thanks.