Hello again PJLTEST,
Thanks for sharing this issue about the bumpers of your Surface Duo. So far, this has been an uncommon issue with the bumpers, but no worries we'll be making sure that this will be acknowledged. In the meantime, if you'd notice that your Surface Duo accessory show physical damage then you could always request a possible exchange. We suggest to contact Microsoft Surface Support to seek exchange options for the said bumpers. If you're located outside United States, see Global Support.
Best regards,
StevenK