These are computers we're talking about. It could be something as tiny as an extra space somewhere (which you can't easily see) or anything like that that it's flagging as a contact information mismatch. It's checking character for character, not for something that means the same. (For example, if you have something abbreviated in one place and more fully spelled out in the other place, the computer would tend to flag that as a mismatch.)

I haven't tried this myself with AA/AS, but in other circumstances I have a devil of a time because of a long street name with getting address matches (where address matches are needed). Everyone abbreviates my street name differently.