ParticleCombiner happily duplicates particle candidates when using cc on particle that is its own antiparticle

Example:

jpsis = ParticleCombiner(
        Inputs=[muons, muons],
        DecayDescriptor="[J/psi(1S) -> mu+ mu-]cc",
        CombinationCut=combination_code,
        CompositeCut=vertex_code,
        name="Jpsi_Combiner")

This always creates two candidates out of tracks/vertices passing the selection. For these kind of particles the parsing should either emit a warning or ignore the cc.

RTA-DPA general meeting from 16.12.2022 favours ignoring the cc in these cases.

/cc @ldufour