Effect dual role

I hadn't seen this for years until it was on TCM tonight.It struck me that Olivia's son (Jody's) so looked like his father and there was not hint that he was the same actor. I thought 'how unique and powerful that would be that Jody's
story begins with this passionate with a flyer who has such a small role, then my observation that her son looked so much like her WWI love. So as she loved a flyer who was killed over France, now she had a son in WWII who might have the same fate. And how this new girlfriend was a parallel character to Olivia's. So in watching the end I thought "how he looks like his father whom he didn't know
and how clever and logical it would be, to complete the parallel, for the son to be the same actor. That brought me to these reviews tonight and there it was in one of the earliest posts...they were both John Lund. For those who had just gone through WWII, and it had just ended in 1946 when this was made, how powerful and touching this story must have been.