I suspect too, that on many occasions, the clerk or even the minster, can't recall the name of the 'suspect' parent and just records what he thinks it was. I've lost track of the number of times i've found missing parents in registers, where the clerk has not been able to recall the name and instead of guessing, has drawn a line, then continued, perhaps hoping that the mum's or dad's name will come to mind later.
A register in Amport HAM has a number of those and one affected us. Fortunately a will confirmed our suspicions but we're now on another conundrum, in that the varying name occurs at the end of a series of births; is this a step-parent or a blank in the clerk's memory.
For the most part, it was up to the clerk to ensure he recorded all the vital events and we both know some weren't always diligent while others went to enormous effort to ensure accuracy. However, i don't doubt that a lot of entries were from memory, or a scrawled on, ink-blotted piece of paper allowing plenty opportunity for mistakes never mind later transcription errors. and if the writing is different, perhaps a new clerk who doesn't know the family personally.
I'd be very interested to hear if you come on any other Appleyard related data.
Enjoy your transcribing.

I've done a fair bit of it myself and, though rewarding, that old writing/scrawling can be a tremendous test of transcription skills and local knowledge of names. I also found it very therapeutic when my sister was dying.
Tell me, did you come on many Tyas, Tyus births/marriages in Conisbro? Joseph Appleyard's son Joseph [my direct forebear] married an Ann Tyas who was apparently from Conisbro. Her parents were Joseph b. Conisbro & Hannah Lambert b. unkn.
I'll have to get back into researching my Yorkshire forebears but in the meantime i've committed myself to my Devon lot so should stick to that in the meantime.
Thanks for your information, Rob

le durachd
Fionnghal