It's only happened once in the 20 or so years I've been growing..... How about you? Ever get this genetic splice? Its called a fasciation
only in the 'mercia's will this been seen as desirable, its not but wonky genes, at best caused by an infection either bacterial or fungal, some are known to be caused by GA3, rarer these days more the point find the cause then remove ....ugh a scrub down would be good ghood luck