Something seems to be messing with the generation of text within the <title> tags.
Normally, the text generated within <title> </title> is <title> [Taxonomy name] + Page # + [Site title] </title> but your category page title tags use the same thing. Are you using an SEO plugin? That usually messes things up for this.
Can you try disabling all plugins except GP Premium and test again if its still the same?