Incorrect transcription of record
Mary Addison died 01 Sep 1942 but record shows 01 Sep 1943 and registration date one year earlier 02 Sep 1942.
Her headstone shows birth year as 1857 but certificate shows 01 Sep 1858 which may or may not be accurate but is as transcribed.
I would add a note / notes in the Collaboration section detailing the alternative information being provided through different sources, highlighting what you believe to be the accurate event dates. Also, assuming you have 01 Sep 1942 as the death date in the Death section under Vitals (on Mary's person page) you could add a note in the "Reason This Information Is Correct" box, advising that official records incorrectly show the date as 01 Sep 1943. This might stop another user from changing the "correct" date to the one recorded in the source.0