At eclipse marketplace at
https://marketplace.eclipse.org/comment/6937#comment-6937
a user mentioned a problem, this is just copied text to an issue:

In most editors in Eclipse (e.g., the Java editor), one can "clone editor" and end up with two editors to the same file (especially useful for editing different parts of the same file). In this application, using "clone editor" ends up with separate instances or something such that making changes in one editor instance are not reflected in other. Furthermore, it makes it such that one cannot switch editor instances if one has saved in one of them as the other is out of sync with the file system.