In contact list, there is a field to put the "Phonetic Last Name". My guess is that it's there so siri doesn't mangle a name when trying to pronounce it. The problem is that if you type in how a last name phonetically sounds and that just happens to have a different first letter than the name .... say a C instead of a K, it will move that contact accordingly. In other words, if you have a last name that starts with a K but sounds more like a C and you type that in the Phonetic Last Name field, it will move your contact location from K to C.