I want to reuse a same script in another chain.
So the new result :
2 chains containing each the part XD02_20211006 (= double use of script).
In that case you will need a 'single' version of that script (meaning with no attachment to any chain) saved twice on your machine.
In other words, to re-use that script in a different chain, you still need one version of that script outside of a chain
To avoid a change of name, I would suggest to save that same script in 2 different location then make both your 2 chains
If you want to save individually a script that is already part of a chain, you will need to un-chain it first
Open the script in Studio
Click on chain script in the Run Tab
Remove the chain by clicking on the red cross of each script