Bing did link multiple sitemaps - should only exist once

[tonqa]

Bing indexation did automatically link to a sitemap called {domain.com}/sitemap.xml/sitemap.xml. This is not intended. I wonder why {domain.com}/sitemap.xml/bla works in the browser. Please turn that off, because sitemaps should only exist once for the website. There seems to be a wildcard somewhere.