Weird Soc.Sec. # Appearing On Credit Report?

Recently my husband checked his free annual credit report(Experian) and we noticed a section that states Social Security Number Variations and has a number there.Well I checked the social security number on a SSN Validator and it came up as being issued in Missouri between 1956 and 1957 well my husband wasn't even born until 1982.Also,the mysterious social security number that's on the report isn't even similar to his actual one so I know it's not a typo.We also noticed a quite odd variation to my husband's name on the report as well.We are planning on contacting Experian to investigate but in the mean time, Could this possibly mean that some has tried to steal his identity or what could be the reason be for this? Thanks In Advance!