PF Particle duplicate bug fix

A bug was introduced to src/SusyNtuplizer.cc from cms538v0. Due to the way PFCandidateCollections are used in CMSSW, the ntuplizer was being unable to associate identical PF particles in some cases and was storing duplicate objects in the collection.
The bug fix was validated using the relval tool and by actually dumping the PFParticleCollection content.