Aye Brian,
Looks like some wag has seen the opportunity to amend the original OCR by using the text amendment facility to the left of the document screen.
So far as I am aware, as long as you are logged in to the BNA, then you can make amendments to the original OCR scan, to 'assist', or otherwise, other researchers.
Personally, I would just log in and amend the wags humour, without further ado, or leave it and treat it as the traffic cone on the head of the Duke of Wellington in Glasgow!
Good health and happy digging in 2021, Bill