I noticed that the Cardassians have 2 types of Listening Post & Isolinear Scanner
the single Listening Post & Isolinear Scanner used by all the empires & the Cardassian Listening Post & the Cardassian Isolinear Scanner. I think there is a error.

This is a bug in the editor, rather than a bug in the game. The Scanners are set as "buildable by all" and the Cardassian scanners are set to obsolete the normal scanners. But the buildable by all function overrides the obsolete function, so the Cardassians are then able to build both. This therefore means other structures are also affected by this problem.

I've already told Mike about this issue so hopefully a fix will come in a future update.

The scanners need to be set as buildable by all because otherwise I would need to manually set the scanners for each of the empires. This would mean the equivalent of adding an additional 12 buildings to the game database, which would be an inefficient implementation of the structures and could potentially slow down the game.