I am not really sure if I follow so let me trying to explain what I am thinking.
With your assembly you have a part named CU-0634-1.
When you copy that you are going to get CU-0634-1:2
and if you copy again you will get CU-0634-1:3
and if you copy again .... CU-0634-1:n.
That means that part CU-0634-1 exists in you assembly n-times.
If you want to create another part that is similar to CU-0634-1 but not the same then you do save and replace.
If the problem is only in your assembly tree, i mean that the parts are exactly the same like CU-0634-1:4 that I see you have it twice under 6,01 .
I have noticed the same thing a few times after using the command 'save and replace', that the name in the
assembly tree hasn't changed but if I open that part it has the correct (new) name.
Y