Sarah Gitel Gersun (Blankfield) - Birth and death dates

I'm not sure where the 1936 death date came from - the death certificate I've uploaded shows 1965.

As for the birth date - that is trickier!
Her death certificate lists her as 78 on 7 March 1965, and her birthdate as 1 Sept 1886 - with 1887 written below that.
The marriage certificate lists her as 22 on 16 Oct 1910. If she really was born in September, this would make her birth year 1888.

Meanwhile, I think I know where the 1882 comes from - a search on JewishGen that shows Sore Gite as daughter of Iosel Blankfield in Lithuania lists her age as 32 in 1914 - giving a birth date of 1882.
It is very confusing. Appreciate any help in solving the puzzle.