Retargeting adds blend targets to the Skeleton Editor Anim Curves. why?

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hi
My retarget system does not separate the body and the face, but is subordinated to the body and used.
What I’m curious about
When you retarget, the corresponding retarget anim curve is added to my skeleton editor anim curve. I’m curious as to the exact reason.
And the AnimCurves I’m not using don’t want to be added. Is it possible to disable the addition of unwanted Anim Curves?
Also, is there any performance impact if these unnecessary AnimCurves are added?
Does it matter if I delete it?