Florent is spelled Schmitt, which may help to tell them apart.

R. Strauss's "Parergon" and "Panathenaenzug" were written for P. Wittgenstein too, as you perhaps know. A search of catalogs produced a couple solo piano works for left hand by Saint-Saens (Etudes Op. 135) and Scriabin (Op. 9), predating Wittgenstein but played by him.