According to Mactracker and EveryMac the MacBookPro6,2 models have a 2 core CPU. The Apple Discussions thread how many cores? suggests to see for yourself with SP (as you did), but joins EveryMac's description by specifying the MBP6.2 models as having 2 physical cores allowing 4 virtual cores or threads. There's the core of your seeming discrepancy.
