how come when some reruns of shows go into syndication they make a different closing for the show because the original closing had the sponsors logo on it (THE ANDY GRIFFITH SHOW, MAYBERRY R.F.D. and GOMER PYLE: U.S.M.C. for example) but other shows (THE DICK VAN DYKE SHOW, THE DONNA REED SHOW and MY FAVORITE MARTAIN for instance) cover the sponsors logo with something?