Of course! And those are properly versioned. Have you ever diff'ed 2 excel files ?
Users need to understand the consequences of doing things "the easy way"
People are used to save every 5 minutes, even on share point this completely defeats any versioning.
Hm... Sorry for the late answer, but why do frequent saves defeat versioning? I think it should help versioning, because a smaller amount of changes will be lost in case of conflict...