Pretty sure both are SATA 3 on Late 2011 models. Early 2011 models were split, some had SATA 3 and SATA 2 optical, others had SATA 3 both.
I did more digging on this issue and it appears the ODD in the early 2011s don't support SATA 3, and the late 2011 15" and 17" don't either. However, the 13" late 2011 ODD supports the SATA 3 6GB/S.
To keep it simple:
MacBook Pro 13 October/2011 models (2.4GHz and 2.8GHz)
Main Drive Bay = 6Gb/s Good
Optical Bay with Data Doubler = 6Gb/s Good
MacBook Pro 15 October/2011 models (2.2GHz, 2.4GHz and 2.5GHz)
Main Drive Bay = 6Gb/s Good
Optical Bay with Data Doubler = 3Gb/s Drives only, not stable for 6Gb/s capable drives
MacBook Pro 17 October/2011 models (2.4GHz and 2.5GHz)
Main Drive Bay = 6Gb/s Good
Optical Bay with Data Doubler = 3Gb/s Drives only, not stable for 6Gb/s capable drives