I haven't heard "on accident" yet - but if it's out there, I'm sure it won't be long before I do. There must be some law of linguistics about this, but once the erroneous usage becomes established among a small number of key people, it seems to suddenly spread exponentially, even when there is no apparent advantage to it. For example, remember 'way back a few years ago when nobody ever got "bored of" anything? "Bored of" isn't significantly easier to say than "bored with" - so why has "bored of" taken over? (Rhetorical question!)