Remove from a list duplicate values

I have a list of data, where some values are the same. Do you know how to clean it up? (without flat the list).

This is technically speaking not a list, but a data tree (or list of lists of points). What you point to in your screenshot, are not duplicate values, but empty tree branches.
If you want to remove these, you can use the ‘Clean Tree’ component. It can be found under ‘Sets’ in the ‘Tree’ submenu. Its ‘T’ input is where your data tree of points goes. Input ‘E’ should be set to ‘True’ to remove the empty tree branches. Also check the other inputs, since they do manipulations of their own, which you might not want. Your data tree won’t be flattened this way.