For example, The SEO Document Editor displays
"Welcome | pimcore demo", while the document only contains "Welcome" in "Settings" / "Name & Metadata" / "Title".
This seems to be because of
in the layout file.
However, if you edit the title in the SEO Document Editor, "Welcome | pimcore demo" is put in the Title field, which after appending "pimcore demo" leads to the title "Welcome | pimcore demo | pimcore demo".
The title is extended every time I edit it via SEO Document Editor, even if I don't change anything.