('CID100003121', 2),Di-n-propylacetic acid
('CID100003121', 2),DI-n-PROPYLACETIC ACID
('CID100007991', 2),Propylacetate
('CID100007991', 2),Propylacetic acid
ldiff: defaultdict(<type 'list'>, {'CID100003121': [9, 9], 'CID100007991': [0, 4]})
f1: [9, 9]
f2: [0, 4]
c1: Counter({9: 2})
c2: Counter({0: 1, 4: 1})
The chosen was  ... CID100007991