  This paper is a summary of my talk at SPIE2013. The organizers were kind
enough to invite me to talk about anything I wanted, and I chose to bring up
the notion of higher order complementarity and the fact that it may not be
monotonic. I enter this discussion, which is rather speculative at this stage,
by calculating a specific example. This is to be regarded as work in progress.
  We analyze a two-particle state and show that when mismatching the detector
frequency response and the field frequency spectrum, several anomalous features
become apparent. In particular, while we find several well known features, such
as $g^{(2)}(\tau=0)=1/2$ for completely indistinguishable particles, we also
find that as the photons are slightly separated and may be distinguished,
$g^{(2)}$ may oscillate as a function of the detector bandwidth. Beyond the
latter interesting observation for which we cannot find a simple physical
origin, we also suggest, an interpretation with regard to an oscillating
$g^{(2)}$ complementarity.
