I've seen Patsy's handwriting. Her natural printing style isn't the same.
It's short/stubby and mostly straight.
Her writing with the left hand produced very sharp zig zaggy writing. It didn't look like the note at all. Just a few instances here and there that would happen to anybody due to chance, writing with their left hand with a sharpie marker, but not overall consistent trends that happen over and over again.
If she did disguise it, then it's a pretty big coincidence because her "disguised writing" looks just like Karr's. She started doing hooks all over the place, slanting her letters the same way Karr did, and weird looking and's that she didn't do in her natural writing.