Sorry for the issues.. to remove the green or double icon just delete the file /home/user/.local/share/applications/2g3g_app_harmattan.desktop, as flake said.

I made a new version that should fix the problem. I've also added a control panel in Settings > Application > 2G3G, so there's no need to use gconf anymore.

Installer: 2g3g_0.2.0_armel.deb

The first version (0.0.1) is also available on Ovi http://store.ovi.com/content/258639, I'll submit soon the new one