joan langbord , in her mid-80s , and sons win back ten 1933 double eagles .
family had brought rare coins to secret service when they were taken .
coins from langbord 's father israel switt had been in a lock box until 2003 .
very few of the $ 20 coins exist because fdr ordered us off gold standard .
government said switt stole them , though he could have traded for them .