Making a duplicate of a substack?

[Doug Lerner]

I have a stack I want to duplicate (copy? clone?) and then save after
changing the stack's name, so I can use it for something else without
modifying the original stack.

I want to make it a substack of the main stack, in the same file as the
original.

I am trying this with the clone command.

But every time I try to change the name of the cloned stack it reverts back
to "Copy of XXX".

And every time I try to save it I am prompted for a separate file to save it
in.

Is there a way of duplicating a substack, changing its name and then having
another stack, like the original, in the same file?

By the by, in 2.12 the object/stack/card inspector doesn't seem to recognize
it well whenever I change my focus using the pointer tool. I often have to
"kick" it by manually selecting something in the Inspector Window. Do other
people experience this problem as well?

doug