  We consider an electronic Hong-Ou-Mandel interferometer in the integer
quantum Hall regime, where the colliding electronic states are generated by
applying voltage pulses (creating for instance Levitons) to ohmic contacts. The
aim of this work is to investigate possible mechanisms leading to a reduced
visibility of the Pauli dip, i.e., the noise suppression expected for
synchronized sources. It is known that electron-electron interactions cannot
account for this effect and always lead to a full suppression of the
Hong-Ou-Mandel noise. Focusing on the case of filling factor $\nu=2$, we show
instead that a reduced visibility of the Pauli dip can result from mixing of
the copropagating edge channels, arising from tunneling events between them.
