Merge Altium Schematic Libraries (and PCB libraries)
I'd recommend using Altium's excellent scripting capabilities, there are plenty of examples here (and other places), including one for 'Delete Selected Library Items'.  I would take one of these scripts and modify it for your purposes.

Or write your own script to de-duplicate the libraries in-place without copying (I know I've written one of these myself in years past, but I've no idea where it is right now - I'll see if I can find it)

The basic script is simple (pseudo code):

Open lib
Loop through components in lib
  If it's name ends in '_1' and various fields are the same then
    delete it
  end if
end loop
close lib


Link: Collection of Altium Scripts