I think the time should match my B machine clock?
I'm honestly not sure. I would expect that the documents, being created on machine B, would have the timestamp already generated with machine B's clock, before it's sent off to machine A. But that's just my assumption, I have no idea if that's true. If the clocks are off though, especially off by 10 minutes, then you have the answer. Either way, it's worth syncing the clocks up as much as possible.