The plural of mouse is, of course, mice. Well, it is if it refers to the little, furry animal. But what if it refers to the computer gadget? Now, of course, we usually only talk about a singular computer mouse, because most computers only need one. But how about a shop that sells the things? Does it sell computer mice or computer mouses?
According to Wikipedia (here), both mice and mouses are acceptable, though some technical writers prefer to avoid the issue by talking about mouse devices.
Actually, it is not uncommon for a polyseme (a word with two distinct but related meanings) to have different inflections depending on the meaning. For example, the past particle of hang is hung if it refers to putting something up on the wall but hanged if it refers to a a criminal being executed. I can't think of any examples (apart from mouse) involving plurals, but I am sure they must exist.