lfstamper

I pieced a king size duvet top for my DDIL. I am thinking I need to put a layer of muslin (or something thin like a sheet) inside to protect the 1/4" seams from wear and tear. since it is king, it is already big and will be heavy if I do too much...If I do this, it would be 3 layers of fabric (top, middle and back). Do you think I can just add the back, and no middle layer? Any one else made a duvet from a pieced top?

Thanks for the help.