I tried to roast 400g of Tanzanian Kilimanjaro AAAB today.
Inspecting beans after the roast I can see some beans are a bit darker, sometimes one side only.
Are these early signs or scorching?
The drum was running D9 all the time. 230C charge temp for 400g.
To my eye, it just looks like you have quite a bit of variability in the degree of roast for those beans. The dark ones seem to be uniformly darker. I consider scorched beans as having a discrete area that is very dark surrounded by a lighter zone.
A lot of the Tanzania listings that I have seen are not a single varietal of bean. If they are mixing varietals, there could be differences in density that could show up as color differences.
How does it taste?
The taste - I haven’t tired them yet - roasted today, going to wait at least few days. 
