Why can this happen ? Have you had such an experience with 2 apparently equal displays?
I've written firmware to control various displays. The parameters vary by quite a bit.
Take RGB displays, for instance: There are a few displays with the same controller, but different subpixel arrangements. If you swapped it without changing the controller firmware, you'd get a rather wrong image. The same applies to monochrome displays, but more subtly - the drive voltages can differ, some controllers are slightly wider than the display (132 px wide vs 128), and the connectivity can differ leading to a cropped image, etc.
Have you tried to get an original replacement, or to get the device serviced by the manufacturer?