But you would never find any language where let us say the -er morpheme in teacher which is derivational, the plural form would also have a marker like -s that is not going to work.
लेकिन आपको ऐसी कोई भाषा नहीं मिलेगी जहां पर टीचर का -इ आर मोरफीम जो derivational है, और बहुवचन रूप का -एस अंकन हो।