Harrison Marriage

Hi, I am hoping someone may have come across this before.  One of my potential ancestors, James Harrison married Bridget Downey in 1837 Ballingarry.  I have their marriage record and the baptism record of one child, Hannah.  I've been unable to find any other records for James.  A few years later I have John Harrison marrying Bridget Downey and baptism records for six xchildren.  Is it possible that James died and a brother John married his wife?  Was that a custom?  I have DNA connect to John and Bridget.  Thank you.  Kevin Harrison