Looking for Alexander Ashby of Royal Victoria Hospital Netley Hampshire UK

I have a marriage cert., for Alexander Ashby to Martha Winfield 1879 in the district of South Stoneham, Hampshire, UK.. he was a private in the army corp at Royal Victoria Hospital, near Gosport...but have been unable to trace him after this event..... I also have record of Martha Winfield marrying the following year to an Alexander Costello who was from Gosport in London. Her father is given as William Winfield on both certificates...Do I have two Martha's or a death/devoice.....Would be very interested to learn more about Alexander Ashby..