Is there a way to turn off auto enumeration in the World Outliner?

I have a specific nomenclature that I wish to keep when duplicating actors.

EX:

X_1

-Y_1

-Y_2

-Y_3

After duplication:

X_2

-Y_4

-Y_5

-Y_6

I wanted for the structure to stay EXACTLY the same after the duplicate.
Is there a way to do this?

Thanks in advance!