tks Jim - and the term "second sun" on this website refers to Nibiru, on the far side of the sun, reflecting light from our sun?
Not exactly. I think of "second Sun" as being a light source in space or atmosphere that is not the Sun.
Now, zetatalk.com claims that PX is between Earth and Sun, offset from a straight E-S line That offset had been to the lower right, as seen from the Northern Hemisphere (upper-left in So. Hemi.} for many years, but has recently moved around due to multiple factors.
The main factor, as I recall at the moment, is that most of the light from Nibiru that arrives to us is not from the planet itself but rather from the swirls of moons and debris that accompany PX. The two main swirls are what are depicted as wings on the planet in many illustrations. Those swirls move about relative to PX planet, and as the system comes closer to Earth, the position of them relative to the Sun as seen from Earth moves further away from both Sun and PX planet.
Another factor is that PX planet does not move in a smooth elliptical trajectory. It jerks at times when it's magnetic field realigns to the magnetic field of the Sun. A report from Russia a few months ago stated that in fact PX has stalled in place for a significant time (weeks or months?) more than once. They had no explanation, or at least not one that Putin was willing to support.