"Duplicate key xxx (attempted merging values xxx and xxx)" exception message during export is confusing

[boricj]

When exporting a selection containing two primary symbols with identical full names, the extension throws an exception with this kind of message:

Exception exporting: Duplicate key _atol (attempted merging values _atol and atol). If null, see log for details.

That error message is confusing and should be reworked to be more descriptive ("Duplicate symbol name _atol within selection") and include more context, like the addresses of the conflicting symbols.