This is a problem. Discourage students from leaving things taped to your door or slid under it. There are too many arguments which arise from disputes over papers that didn't arrive on time or that disappeared. The same goes for teachers leaving something for a student pinned to an office door. This is up to you.
Many teachers have a formal policy which allows each student to turn in one late paper.
Others are very strict about not accepting any late papers. Check with your supervisor for guidance regarding late papers. Whatever your policy, give it to students in writing. It's best to move around. Actually, moving around keeps you and the students alert.