Far more confusing is the fact that he's called Jack Harkness. If he's been hanging round for 100 years or so between the Daleks and Torchwood you can understand how he's got that name, but we know he'd already adopted the name prior to The Empty Child. So the actual Captain Jack must have met our Captain Jack at the same time as the immortal Captain Jack was on the Earth, knowing of the meeting et al. Therefore the non-immortal Captain Jack must have met the one he took his name off at some point after the time-slip Torchwood episode. In which case didn't the real Captain Jack recognise him?