We all make mistakes, transcribers and the original form writers (whether they be parish clerks or census enumerators) included. As we know, it’s important to check original documents whenever possible and not trust in just the transcription, but sometimes the details on original documents should be taken with a pinch of salt.
I would imagine that most people researching their family history have come across a few transcription errors – usually names that have been mis-transcribed from difficult to read old handwriting. On the 1911 census, my great grandmother Kate is listed as Rate, her brother Uriah is Vira and her sister Eunice is Marck.
Sometimes errors are not the fault of the poor transcriber (I have done transcribing, and it can be tedious work). When I was researching my 3 x great grandparents I struggled to find them on the 1871 census. Luckily I found one of the children’s marriages in 1870, his address was listed and a search for that found the family – their surname of McAndrew had been transcribed as McKandy on Find My Past and McRandy on Ancestry – this turned out not to be a transcription error though, but instead a case of the enumerator not understanding their Irish accents.