Longarm quilters sometimes use (2) layered battings { often a cotton and a wool} to show- highlight their quilting. Using 2 battings really enhances the stitching - ( will also help any mistake jump right out at you!) If you just want loft buy one batting with higher loft.... There are many options. If you are a terrific quilter wanting to showcase your stitches for a show by all means layer a couple batts... If you have a longarm....much more difficult to quilt with a domestic sewing machine.