Moving xmpp account contacts to a new account is possible on Linux with the pidgin plugin listhandler. This can be done with a graphical user interface, no command line usage is required. The pidgin plugin is also available via apt: `sudo apt-get install pidgin-plugin-pack`.
Install the package and exit pidgin via `Buddies` -> `Quit`. Start pidgin again. Open `Tools` -> `Plugins` and see if `List Handler` is enabled. If you have a lot of plugins, you can just type “list” while having the focus on the plugins window, and it will just to the plugin (if it is there).
Now go `Tools` -> `List Handler` (this should now be at the bottom) -> `Copy buddies from one account to another`. You have to be online with both your old and new account in order for this to work.
When not all the Buddies are shown in the new Account, check that `Buddies` -> `Show` -> `Offline Buddies` is activated.
It is also possible tobackup your pidgin buddies via `Tools` -> `List Handler` -> `Export generic buddy list file`.