I would have expected the 128K Badge to have been replaced as well. But who knows what happened. Perhaps the original user asked for it not to be replaced, or kept the 128K Badge and later replaced it themselves on a whim or for nostalgia, or whoever sold it swapped the badge in an attempt to get more money for it (the label being virtually impossible to replace at this point). Or perhaps the tech was lazy and just performed the minimum required by law - switching out the agency label. Yours is obviously better than most as I have seen some where the new label was pasted directly over the original label. To answer your question, I have never seen this combination, and there is no "official" reason I can think of that would account for this configuration. If such a thing does exist elsewhere, it is stricly serendipitous.
Just to clarify - the badge reads "Macintosh 128K", NOT just "Macintosh", correct?