[Dovecot] Strange Problems when deleting folders.

Hi

I'm experiencing a strange problem on my dovecot 2.0.21 setup.

When i delete a folder "foo" it was correctly moved in the trash folder. If i try to delete from it the folder "foo" from the trash it gets renamed "foo1".

If I try to dlete "foo1" it gets renamed foo11, and the operation could be continued figured out in an endless loop.

This happens both from thunderbird and sogo (a webmail).

Is it a known bug or a misconfiguration ?

Thx in advance