Despite what the 1861 census says, Harriet was not yet 8 yrs old at the 1861 census and at the times of the 2 marriages she was not yet 18. Note that the first (jncorrect) marriage was just 8 daysafter the 1871census, so she knew her name was Ellison
I wonder if she was confused by the fact that her real mother was Isabella and her aunt was also isabella. And maybe at the time of the first marriage she did not know her real father name so she used Thomas Richardson. Once the error was realised the only way to put it right would be to have a second marriage with the correct names
Dave

Hi Elaine, Bigamy was common in those days as normal people could not afford to pay for a divorce. I have quite a few in my tree
Best wishes, John

Think we now have it sorted for Kathleen......... and I dont have to be concerned about our transcription being incorrect.

Phew that was a brain teaser. LOL

Elaine.