In any case, a few minutes checking shows the whole story to be bogus... Apart from an approximate agreement in orbital inclination, the two can hardly be described as "nearly identical".
The conclusion is not proven, but the evidence is sufficient for the editor of Spaceflight:
"Space-to-space surveillance is a whole new ball game made possible by a finessed group of sensors and sensor suites, which we think the X-37B may be using to maintain a close watch on China's nascent space station," said Spaceflight editor Dr David Baker...
..."The parallels with X-37B are clear," Dr Baker says in Spaceflight, the long established magazine of the British Interplanetary Society.
"With a period differential of about 19 seconds, the two vehicles will migrate toward or against each other, converging or diverging, roughly every 170 orbits."
Consequently your reference to the relative positions of the two craft, while thoughtful, appears to have led you to an overly hasty conclusion. And apart from the professional analysis referred to, there is no doubting the motive.
reply to post by zorgon
X37B can change orbits at will though I doubt it is spying on China's platform. We have better satellites for that
The contention is that new surveillance technology is being tested/used beyond the capabilities of what has gone before. Even NASA admits to that much (—just refusing to say for what purpose).
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