How to copy one list to another AND preserve the original list

This is technically a guide but a bare bones one so I have left it in Discuss. It’s more about what I figured out which may help anyone who’s ever been in the same situation.

I created ListB at Screen1 Initialise and was using the following blocks in a procedure:

This was to copy one list to another. However the original list (ie ListB) kept getting deleted and I had to keep recreating it.

Finally I figured out I should be doing:

This allows me to create List B upon Screen 1 Initialise and copy List B to List A and do whatever I want to List A (which involves removing its elements randomly until its empty) and then doing it again whenever necessary without having to recreate List B.