Select an rtf (“File #1”)
Select some text in it
Hit Cmd-C
A new rtf is created inside the file parent, with the entire contents of File #1
EDIT:
Sometimes just selecting the text causes a new rtf to be created
Expected: nothing, text copied to clipboard.
You’ve got some process running, not a native behavior of DEVONthink 4.
What kind of clipboard/automation utilities do you have running?
Sounds like a PopClip extension gone rogue.
Thanks Jim, that makes sense. Keyboard Maestro, PopClip - but I did add DT4 to the PopClip exclusion list…
Unless it is some rogue AI? 
I think Nick would have to answer more on that. PopClip could be using the old com.devon-technologies.think3 bundle id for the exclusions as well.
Haha! No external AI is running silently in the background.
Yep, I spoke with him - he’s looking into it - but he did tell me to add DT4 to the exclusions. Well, Sorry PopClip, I love you, but I love DEVONthink WAY more 
Disabling PopClip for now
Not PopClip. Trying to find what else…
Disable KM.
yep, disabled it too, plus a couple other things, seems to have fixed it. Now to find out what did it.
Thanks Jim! (and sorry for the non-issue)
No worries!