  We study four-dimensional N=1, 2 superconformal theory in class S obtained by
compactifying the 6d N=(2, 0) theory on a Riemann surface C with
outer-automorphism twist lines. From the pair-of-pants decompositions C we find
various dual descriptions for the same theory having distinct gauge groups. We
show that the various configurations of the twist line give rise to dual
descriptions for the identical theory. We compute the 't Hooft anomaly
coefficients and the superconformal indices to test dualities. Surprisingly, we
find that the class S theories with twist lines wrapping 1-cycles of C have the
identical 't Hooft anomalies as the ones without the twist line, whereas the
superconformal indices differ. This provides a set of examples where the
anomaly matching is insufficient to test dualities.
