I use Thunderbird 1.5 RC1 german: Virtual folders that contain a space in the name (i.e. "Apple Discussions") are sometimes duplicated. The second folder than has %20 instead of the spaces (would be "Apple%20Discussions" for my example). But this is not forever, after a restart of Thunderbird this behaviour can be away. I attach a screenshot to make this clearer.

See this on linux too. Seems it only happens the first time you come from 1.0.x to 1.5, after that everything is ok.

Well, I used my TB 1.5RC1 for many times, and I saw this behaviour more than once.

I'm seeing this too when i move back and forth between trunk and branch builds. This should really be a thunderbird 3 bug since that's the next release from the trunk but we don't have a milestone field set for that yet.

I have 5 accounts (3 POP and 2 IMAP) configured in my Thunderbird 1.5 RC1. I have the feeling that this misbehaviour happens, when a logon on one account takes a long time, but I am not really shure. On another computer have one IMAP account with an RSA-generated onetime password, so I have to enter the password each time. While the password dialog is shown, I also see those duplicated folders, but when I entered the password, the second one with %20 instead of spaces in most times disappeares. I hope this helps.

I feel like we fixed this on the trunk and the Thunderbird 2 branch when we fixed the problem where virtual folders weren't showing up in favorites view and others. Care to try again with a thunderbird 2 nightly? ftp://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-mozilla1.8

Well, I did not test it with Thunderbird 2, but I do not see this in the latest stable 1.5 version (1.5.0.6).

per reporter