a = pd.DataFrame([[1,2], [3,4]], columns=[0,1])
b = pd.DataFrame([[5,6], [6,7]], columns=[1,0])

a[[0, 1]] = b
print(a)

0  1
0  5  6
1  6  7

0  1
0  6  5
1  7  6

a.loc[:, [0, 1]] = b
print(a)
   0  1
0  6  5
1  7  6