I catch in Google Analytics that some entries are duplicated and some don't:
For duplicated entries, one has site name in its and one doesn't. Further investigation shows that for titles having site name in them, their URLs have correct case (e.g. /Trấn Kỳ/Hướng dẫn sử dụng Trấn Kỳ/), while for titles not having site name in them their URLs are lowercased (e.g. /trấn kỳ/hướng dẫn sử dụng trấn kỳ/).
What make them lowercased? Why does that make the title not containing the site name? Why don't they lowercase all at once?