Question ???

I was rereading a letter I rec'd from the US Army concerning the medals my father had been awarded during WW II, what caught my eye this time around was the fact that they stated he was awarded a "Good Conduct Medal" for service from 1937 thru 1940 and from 1940 thru 1943.

What I did not understand was all the documents I have state he joined the National Guard in the early part of 1940 (69th Fighting Irish) and then was mobilized etc.

Am I missing something??

Please Help


P.S. He was also awarded the Silver Star, Bronze Star, Purple Heart etc.

Any help would be appricated.