Different namedtuples unify?

[MIvanchev]

Is this intentional?

ntuple1 = namedtuple("ntuple1", ("a", "b"))
ntuple2 = namedtuple("ntuple2", ("a", "b"))
unify(ntuple1(1, 2), ntuple2(var(), 2))

What would be a good way to define distinguishable forms?