Descriptor difference on the same keypoints

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I am getting a different keypoint angle when I am trying to compute the same thing in 2 different ways:

1.

detectAndCompute(img1, noArray(), kpts1, noArray(), false);
detectAndCompute(img1, noArray(), kpts1, desc1, true);

2.

detectAndCompute(img1, noArray(), kpts1, desc1);

I am getting a difference only on the keypoint angle (not a significant), which makes also descriptors to be different.

I am using KAZE keypoint extractor (OpenCV 3.0.0)

Any help on this?

Thank you.