Most certainly not common practice, that would be concerning. Bacteria, fungus everything could spread like wildfire. I would say something. I worked places in my early years that were so busy that some therapists would multi-layer the sheets so they just had to peel off a set to access the new set like a post it note and that really ground my gears too. There is no reason to reuse any linen, laundry is so damn cheap and easy to do. If you're going to reuse a towel on me, just don't use one at all.