PLX 1000 out of synch reset button

Hi Guys. I have noticed that that playing identical records on identical decks, identical stylus etc etc even with the reset button pressed on both decks the tracks still slip out of synch with each other is this normal? After around 30 seconds on them being in time they start to slip out of time even though they are identical vinyls playing on PLX 100 decks with reset button pressed.

Check out the video. The strobes are not moving so looks like the decks are both at 0% but its not so.

https://www.youtube.com/watch?v=URIMjXWOSpA