If Raymond Rutherford Roberts Born Dec 1919 in Maryland is your Capt Roberts then he enlisted prior to Dec 7th 1941, Pearl Harbor as a Private, Aug 11, 1941. Go to http://aad.archives.gov/aad/series-list.jsp?cat=WR26http://aad.archives.gov/aad/series-list.jsp?cat=WR26 the NARA Access to Archival Databases then in search box below green bar with Search WWII type Roberts Raymond R and there will be 17 results, then click the view records. Click on 2nd Raymond R Roberts with Army serial number 13042832.
You can use this information to file a request for his service record at the NARA. www.archives.gov But they had a fire in 1973 and abt 80% of Army/Air Corps records of WWI personnel (as well as earlier and later) were destroyed, so they will send you what they have.
What is the difference in the dogs tags? Could be he was issued another one when he was promoted to an officer from enlisted ranks.
Check with the local VFW, American Legion and other Veterans Organizations to see if him belonged to any. Check the county Veterans Affairs office where he lived after his discharge,(and later). Some Veterans filed their DD214s with that office to recieve GI Benefits, state and local.