I would also add that "three of them spotted" isn't a big deal, if the distinguishing feature of note is: "three KJ-600s in the same satellite photo taken at a single moment".
For example, in January 2022 on GE we can see three KJ-600s on the Xi'an/CFTE lot, just separated across the facility but taken in the same image. I.e.: as early as 2022 there were at least three individual airframes that existed.
Broad picture (note the three small red squares, two on the top left hand corner, one on the right hand side near the edge of the image)
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Zoomed in on the two in the top left hand corner:
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Zoomed in on the one at the right hand side near the edge:
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