Flipping image to create canvas with simmetry

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i'm using Python cv2 to create a canvas image based on a small part cutted and flipped. This is an example of image:

than i crop a small part of the left side

crop_image = test[:, 0:70,  :]
crop_flip = cv2.flip(crop_image, 1)
test_points_1 = getOrderedPoints(crop_flip)
mat = cv2.getPerspectiveTransform(test_points_1, style_s4h_side_points)

And merge the base image and the flipped part with a template i have got obtaining this output

The problem is that on the left side should be just a mirror and there should be symmetry between lines. How can i solve this problem? I tried moving points but i deform the base image. Thanks!