RJ TextEd

I have two files and want to compare them; now one is in the left view and another one in the right view; differences are highlighted. I decide that the "right" file has a "correct" line, so I place my caret on the line in question and click on "copy left" icon. Now the "left" file has this line, too, but the "right" file's tab is marked as "changed"! After a few seconds also "left" file tab has little yellow square. When I want to close "right" file, modal window informs me, that its content has changed (even though it, of course, hasn't).

I "save" both documents; they're now identical. I click on "Re-Compare" icon and now again both are yellow ("active" one immediately, another one when you click on it). I haven't done any changes, though.

OK, so I click on "save" icon with a caret in the "right" document; tab's mark turns to green. The other one, when I click on it, follows.