For inconsistencies like these in the ISC catalogue, you may wish to contact James Harris at the ISC (email: james@isc.ac.uk) who will likely be happy to check this for you.
I would asume that the "?" in the phase_hint for the second pick makes it more likely to be a questionable/preliminary/automatic observation.
Dr. Stephen Hicks
Postdoctoral Research Fellow in Passive Source Seismology
University of Southampton