Nothing wrong with using 'do do" but it just sounds like something doggies do. :-)
The above sentence: I don't do anything I am ashamed of, but sometimes I do do things I find embarrassing.
I don't do anything I am ashamed of, but sometimes I do do things I find embarrassing.
Might sound better if said this way: I don't do anything I am ashamed of, but sometimes I actually do things I find embarrassing.
I don't do anything I am ashamed of, but sometimes I actually do things I find embarrassing.