From This Day Forward or The Snake Pit

These two movies have at least two similarities. First, Mark Stevens plays the lead in both films. Second, the female lead in FTDF is Joan Fontaine while the female lead is TSP is her sister, Olivia de Havilland.

My pick: Although Joan is probably my favorite actress of all time, I'll pick The Snake Pit. Her sister does an amazing job playing a mentally disturbed person who gradually regains sanity. I especially like the part where the patients are singing "Goin Home."