Hello.
Oddly enough I've had this issue with video before i.e. two IDENTICAL cameras but over time (an hour) audio streams not identical in length (out by a millisecond or two by the time you get to the end of the footage). This definitely had to do with the clocks (and one of the reasons why pro video stuff has a thing called "genlock").
There's a bit of useless information anyway.
Regards,
Dale.
Phase Issue
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