PowerShell, 66 37 26 bytes
-11 bytes thanks to mazzy
!(($args|group|% c*t)-ne2)
Groups up $l
and iterates through itgrabs all the counts of matching values. It then filters out all counts of 2 from this list. If the list is empty, checking each group'sit's a Noah number; otherwise, it'll be populated still with non-2 counts. Not-ing the list will yield countTrue
to see if they're size 2.it's empty and False
if it's populated