The SEOPageTitle for categories is used, but it's mixed up a little if you have other settings, here's the logic...
strText = GetStoreSettingText(CategoryListInfo.PortalID, "categorypagename.template", CategoryListInfo.Lang)
If strText = "" Then
strText = CategoryListInfo.SEOPageTitle
strText = Replace(strText, "[TAG:PORTALNAME]", PortalName)
If strText = "" Then
strText = CategoryListInfo.CategoryDesc
End If
If strText = "" Then strText = PageTitle
Else
strText = Replace(strText, "[TAG:PORTALNAME]", PortalName)
If CategoryListInfo.SEOPageTitle = "" Then
Dim objTRepl As New TokenStoreReplace(CategoryListInfo)
strText = objTRepl.DoTokenReplace(strText)
Else
strText = CategoryListInfo.SEOPageTitle
End If
End If