Hi miss-bear,
The point I made above is that you need to have the same settings. Taking overshoots out was not meant as a rule.
In the initial example, the Key settings were different for the second Joint than the first. That might work sometimes, but more often, it doesn't.
The first Joint does something that the second joint need to do while countering the movement of the first, as it is a child of the first. Any slight derivation from the settings will lead to different results.
When I select your first example, Keyframe 75 from Joint and Joint.1, the fields show Mixed or [ - ] in many areas. There should only be one Mixed, and that is the Key value. These two values should be like "positive two" and the other "negative one", in ratio to each other.
All the best
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