The new layers will be printed to the left a bit?

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The problem is that almost every new layer is printed slightly to the left on the x-axis. simultaneous print has not had problems in the past (~ 10 prints), when I used pronterface for slicing and printing. Now, I created g-code with Kisslicer and print it with protnerface, the result seen in the picture.

What could be wrong?

I use marlin firmware in sanguinololu board.

Most likely you are losing steps on the X axis, probably the stepper pot is set slightly too low.
The kisslicer GCode is probably just different enough to cause this to happen, the speed settings aren't identical for example.
It could also be too high a speed set in the slicer/firmware, and possibly something mechanical, though that seems unlikely if you've been printing successfully.

Check the pictorial guide, exactly this problem is described in there. Also good for other problems.