Different chessboard corner orders in stereo images

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I have two images where I recorded a chessboard with two cameras with a specific baseline. However when I draw the chessboard corners I can see that on the left image the most left corners are blue transforming to a red on the right side. However, the right image has the most left corners colored in red and the most right colored in blue. So exactly opposite ordering.

How does the ordereing of the detected corners work in cv2.findChessboardCorners()? And what could be the reason that they are ordered differently? I hold the chessboard with the long side in a horizontal position and I use a 6x4 chessboard. My stereo calibration also totally gives wrong results. I assume this is because of the wrong ordering in some image pairs.