>>> a = "a133efb38766"
>>> b = "a0a1a2a3a5a7"
>>> a.encode().hex()
'613133336566623338373636'
>>> bytes1 = bytes.fromhex( a.encode("utf-8").hex())
>>> bytes2 =  bytes.fromhex( b.encode("utf-8").hex())
>>> xored = bytes( b1 ^ b2 for b1,b2 in zip(bytes1,bytes2))
>>> xored.hex()
'000152020454030059025701'

>>> for c,d  in zip(bytes1,bytes2):
...     e.append( ( c ^ d ) )
...
>>> e
bytearray(b'\x00\x01R\x02\x04T\x03\x00Y\x02W\x01')
>>> e.hex()
'000152020454030059025701'