I've tried it with with my Miranda (not the test version with debug symbols), and it immediately found updates for all the protocols, the Dbx_3x and the PluginUpdater (the last one is very strange... this one should be the last version, isn't it?).
No - it's all ok, Dbx_3x - because in code of a new updater is to kill it (we got rid of this database driver) and PluginUpdate itself it "updated" to older version, cause it verifies the hashes on specific repo an syncs with it, any version that differs it will see as "needed to be updated", this way we can prevent all the "zoo" of different plugins and their versions that existed on Miranda IM.
So, you can return the new version, remove the checkbox from pluginupdater component in updates window until the next stable, then you can update it all, including updater itself.
Post Merge: 09 01 2014, 12:48:58
And thanks for a bug-report!