[TYPO3] use extension twice

[freitag]

Hi List,

I´m trying to "clone" a running extension (nicosdirectory).
What I did is:

- copied the folder + renamed it.
- created the needed tables in the database and changed every appearance
   of the old extension key to a new one.

- added the new folder/extension to typo3conf/localconf.php

If I install the new extension with the extension manager niosdirectory 
unfortunately doesn´t output anything anymore. if i deinstall the new 
extension nicosdirectory is working fine.

can anybody imagine where these two extensions get in conflict?
(database query,...,installation,naming ?)

the only error message for the new extension is an naming error within 
the extansion manager. maybe that´s the reason?

thanks a million for your help,

freitag