Do mtb cleats and pedals damage road cycling shoes in any way?

I am new to cycling and wanted to try some clipless pedals. I have bought some road cycling shoes but have been given some mtb pedals and cleats from a friend for which I am very grateful and don't want to seem otherwise. There are holes in my spd-sl road shoes for these but I wondered what the difference was, whether they would damage my shoes hence my question and if I would be better off getting road cleats and pedals instead?