Well, here's the problem. Both pieces can be traced to historical misinterpretation. The first "act" is not locus to Mozart. Any student of the age would, in fact, take previously written, concerto, et al, and rewrite them. The first one postulates the mistake came from a painting.
The second one was a rewrite in order to study the music. The fact that he used it at the time would not have been shocking to a concert goer at the time, because they would have known the borrowed piece. Again, their seems to be an historical miss interpretation. That wouldn't be Mozart's fault, nor is their proof that these were stolen for personal gain vs standard use for a student or an interpretation of music.
Caption this Meme