Version: (using KDE KDE 3.5.8) Installed from: Debian testing/unstable Packages OS: Linux having opera as default browser, every application opening a link (kopete, bug reports) opens _two_ identical tabs instead of only _one_. the command to execute (kcontrol-> kde components -> component chooser -> web browser) is opera -newpage %u which, executed from konsole, yields exactly the desired result: one tab. so, there seems to be some double working when calling via kde mechanisms ...
Fixed in more recent KDE version.