What is the smallest regular map with a Schläfli symbol of the form {p,p} but not self-dual?
It is S4:{6,6}2,3,
or its dual S4:{6,6}3,2.
The former has a vertex multiplicity of 3 and a
face multiplicity of 2; the latter has a vertex multiplicity of 2 and a
face multiplicity of 3.
In the same genus there is also
S4:{6,6}3,3, which
is self-dual, with vertex multiplicity and face multiplicity both 3.
Regular Maps FAQ to which this is one of the answers.