Why are two icons needed to represent a progress of 100%?

[theelectricsoul]

Scenario

With those functions we can add a progress icon to a node. This is very useful.

Freeplane uses two icons to indicate that the progress has reached 100%

Problem

I do not see an advantage of adding a second icon when 100% progress is reached. I only see more icons.

Question

Why are two icons needed to represent 100% progress?

Thanks :)
Robert