Eliza Ann Gray/Mary Gray

[goof]

Just got the marriage certificate for my grandmother's second marriage. She was Eliza Ann Gray at death of her previous husband, but on the certificate her name is given as Mary Gray.
All certificate details about her are correct, her age, father's name, husband's name, place(Tendring) Her parents did not have a daughter Mary.
Does anyone have any ideas as to why she may have changed it?
I am now looking for her death, and don't know whether to search for Eliza Ann (which turns up nothing) or Mary Ann, which turns up as a death in 1923 in Colchester which agrees with what my mother told me years ago.
Thanks.
Geoff.Charge