names = ["tom", "john", "sara" , "tamara" , "tom"]
single_finds = []
duplicate_finds = []

for i in names:
        if i in single_finds:
                duplicate_finds.append(i)
        else:
                single_finds.append(i)

print (single_finds)
print (duplicate_finds)

['tom', 'john', 'sara', 'tamara']
['tom']