I'm not sure that's really a bug so much as an expected result.
I suspect that each of those sections is displaying a pointer to the same object, and any manipulation of the object in one area will be echoed within the others.
This would minimize the amount of code required; it's kinda like a subroutine call?
[My last programming class was in 1982, so my grasp of the modern terminology may be somewhat lacking.]
How often one would open more than one of the three possible display areas at the same time would seem a good question, because one would only notice this if one were doing that.
I was able to replicate it within Chrome on a Windows 10 system.
