i had lots of 20p pices with these errors, i kept them a while, looked at them through a magnifier, enjoyed studying them. eventually i spent them on a couple of pints of speckled hen......there will be somewhere in leeds that sells speckled hen   i was surprised at how many coins in circulation that have soo many manufacturing errors, my experience is that the 20p and 5p seem to suffer more than most.   perhaps this statement is inaccurate however as the 50p coin seems to have almost disappeared from circulation ( around these parts), with millions of rare examples being offered on ebay  . the 10ps ive looked at,  has seen fewer errors, with just a couple of examples found.