'Borg'?
I am from Sweden, but I have never seen the first name "Borg" being used here. Literally it means "Castle", so it's not simply taken from the air. (And the greatest tennis player ever, Björn Borg, had it as a last name.) In some female names, 'borg' may be used as the second element, though: Ingeborg (with the famous short form "Inga"), Gunborg (short form "Gun") etc.
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