Hi I have Audacity version 2.4.2.
And I want to use it to cleanup some audio from a video file.
I had great success using the noise removal tool, but I also want to remove some “blemishes”
Using ctrl-l I can remove unwanted part but the total silence sounds a bit odd.
I would prefer to clone over some of the remaining noise.
Without effecting the total length of the audio. So I can put it back with the video.
I looked in to overlying a extra track with some noise, but apparently that does not work in they way I was expecting. (it always mixed)
But there must be a way. I tried using the envelope tool to silence the unwanted parts but that is just to complicated.
Any suggestion? Because I can not figure it out 
There is Punch Copy/Paste. That may do what you want. Look through this.
https://forum.audacityteam.org/t/punch-copy-paste/28906/1
Koz