Are there any suggestions where these two launchers are hiding?

Some months ago my default panel obtained two konqueror launchers which I can not get rid of.
I can right-click remove the two launchers but they re-appear at the next log-in.
Last week I moved my .kde to .kde.old and re-installed KDE and allowed it to create a new .kde directory
But the two konqueror launchers are still on the default panel.

might be https://bugs.kde.org/show_bug.cgi?id=293240 or https://bugs.kde.org/show_bug.cgi?id=278724

suggest you try: delete panel then add a new empty (not default) one and repopulate it