  We argue that there could be large, SU(3) violating resonance contributions
to D -> K pi decays which would affect the extraction of the D0-anti-D0 mixing
parameters from experiment. Such contributions can induce a large strong phase
in the interference between the doubly Cabibbo suppressed and the mixing
induced Cabibbo favored contributions to the D0 -> K^+ pi^- and anti-D0 -> K^-
pi^+ decays. Consequently, the interpretation of a large, CP conserving
interference term can involve a large mass difference Delta M rather than a
large width difference Delta Gamma.
