The memories of the long dead people who provided information on a 1900-era death certificate can easily be wrong. So can yours.
What things about your ancestors are you using to help you research that might not be true or which you are remembering incorrectly? Are you searching the 1860 census for a relative who died in 1857? Are you looking for an obituary in the 1890s for someone who died in 1902?
Virtually any detail can be remembered incorrectly. What details are you pulling from your head when you should be pulling them from your files?