Since Alzeroth isn't comprehending the screenshot I'll explain for him.
The message says "resonates softly..." which means that it should have been a tier 2 vnm.
Feebly = T1
Softly = T2
Solidly = T3
Strongly = T4
And like Vitali pointed out it will always display the highest color you have. Regardless of what it is tracking.
VNMs have a habit of clustering but you will only get a reading from the one that is the closest. Omari is 100% correct in everything they stated.
Alzeroth, this happens, regardless of how careful you are, they move around a lot and like I said only the closest mob will give a reading. The only way to be sure to avoid it is to hax using programs like APradar.