dict1 = {"group1":["a","a","b","a"],"group2":["a","a","a","a","a"]}
dict2 = {"group1":["1","2","1","1"],"group2":["1","1","2","3","4"]}
result = {k: len(set(zip(dict1[k], dict2[k]))) for k in dict1.keys()}
print(result)
# {'group1': 3, 'group2': 4}