  In diffractive hadronic scattering processes, the Pomeron trajectory,
originating from Regge theory, significantly contributes to the behavior of the
total and differential cross sections; the same holds for the description of
the proton structure function in deep inelastic scattering. So far, the Odderon
as the odd-parity partner of the Pomeron has only been observed in differences
between differential cross sections for p p and p pbar scattering at low t. We
investigate exclusive photoproduction of two neutral pion final states at e+e-
colliders; in this reaction, Pomeron exchange is forbidden by C-parity
conservation. The Odderon is described by an effective propagator. The Odderon
contribution produces significant modifications of the differential cross
sections. We investigate the effects of variation of trajectory and coupling
parameters. We provide numerical results for total and differential cross
sections for OPAL, BaBar, TESLA and the TESLA photon collider including
detector cuts.
