SEF Advance with Virtuemart - Together with XML Sitemaps

Have patience please. It will be looked at.

The products with duplicate links were not added to XML sitemap because you had activated "enable canonical URLs" under XML sitemap configuration (advance settings). When activated it seems to detect the canonical meta tag and only adds the canonical version of the URL.

I deactivated it and now both links are added to the sitemap (if that's what you want).

See www.mrskibbles.co.uk/sitemap.xml
Both are now added:
www.mrskibbles.co.uk/virtuemart/sweet-ca...s/black-jacks-chews/
www.mrskibbles.co.uk/virtuemart/colour-a...k/black-jacks-chews/

It's questionable though if that's to recommend from SEO perspective. I would only add the canonical version of the link to the sitemap, but that's just me.