I only experience them on government and bank websites.

I can see how some naïve users might want the extra-confirmation that they are cancelling this action – but I there's not reason for them to be visually similar and positioned almost next to each other.

a commonly used ticketing system has them, as does a particular bank i know of ...

you'd be surprised to hear that i had a need to use both of them in the same day and they both got me with it...