Hardware-synced cameras will be be triggered using a common clock (crystal oscillator or such). That's the only way to ensure they won't drift apart eventually, little by little. So basically you'd loose stereoscopy at some point, possibly quite soon after the recording has started. I think it's possible they are still synced if they show up as two cameras. I guess no way of knowing for sure. I wrote the manufacturer but no reply so far. I think that one way to test this would be to record a video of a stopwatch (ideally one with millisecond precision) and see if the eyes get out of sync after a while. The longer the video the higher the chance of sync issues to show up. What do you think?