Applying for tenure-track research position and lecturer position at the same university?
In my department, tenure-track hiring and lecturer hiring are done by different committees. When I was associate chair (until a couple of years ago), I was on both committees, but, as far as I can remember, I was the only common member. So if someone applied for both sorts of positions, that fact might not get much (or any) attention.  Also, you shouldn't worry about the tenure track committee thinking you have a low opinion of yourself. We generally don't care very much about your opinion of yourself (some people are naturally modest); we care about other people's (especially experts') opinion of you.