Whilst researching the family of my Great Grandfather, Frederick Williams, I learned from the 1901 England and Wales Census that he had a younger sister, born in 1899. Her name was Margaret Amy Williams and had never married. When the 1939 Register became available for viewing, I discovered her full DOB, which was June 26th, 1899. Whilst searching for her death record, I came across a 1993 death info, which had the correct birth date (26/6/1899), same first and surname, but the middle name was "Ann" instead of Amy. Could I be a looking at the wrong person or could there have been some sort of error or misunderstanding with the middle name?
First, investigate the birth registrations (using the GRO website -- free but you do have to register) for Margaret Amy Williams and Margaret Ann Williams in the June and September quarters in 1899 (both quarters because she was born so close to the June quarter end) and compare the maiden names of the mother with the maiden names of Frederick Williams to see which are possibly his sisters (assuming they shared a mother). As (based on my search of the 1939 register) the family is Welsh, this may not be diagnostic. However, I note that there were no Margaret Amy Williams births registered in that year.
Next, review the evidence that leads you to believe Frederick's sister was Margaret Amy. In 1901 (if I have the right family) she was indexed by Ancestry as Margaret A; and in 1911 as Margaret Amy. However, when I inspect the census image, I would say the name is Margaret Ann. Findmypast agrees with me, but theGenealogist says Margaret Amy.
Given the fact that no births were registered for Margaret Amy in 1899, and the census evidence could support Amy or Ann, I believe the death you have found is the correct one and the correct name is Margaret Ann.