"Every once and again our justice system fails..." (http://www.dailymail.co.uk/news/worldnews/art...)
"We have declared once and again that the conflict between Armenia and Azerbaijan must be settled peacefully." (http://www.dealchecker.co.uk/cheap-flights/to...)
"Death–and he drove in his spade once, and again, and yet again. " (http://www.hedonistic.co.uk/huxley/bnw/eighte...)
"Now America is down once and again...., " (http://www.guardian.co.uk/commentisfree/2007/...)

"once and again" findet man nicht bei leo...
es scheint in den obigen beispielen folgende bedeutungen anzunehmen:
"von zeit zu zeit", "dann und wann";
"wieder und wieder"; "wieder einmal"; "zum wiederholten mal";
aber wohl nie die gleiche bedeutung wie einfach "once again": nocheinmal...
oder?
danke!