Songbird adds ID3 v1 Tag automatically

Platform is XP SP3, Songbird 0.7 RC2,but this problem seems exsting for a long time not exactly in 0.7.
I know Songbird's metadata editor writes ID3 v2.4,but my mp3 file all converted with Tag ID3 v2.3 UTF-16.
when I play these files with Songbird, sometimes(not everytime) after a file being completely played, it would be added ID3 v1 tag beside original ID3 v2.3 by Songbird.

And when I creat a new profle, and after imported these mp3 files, songbird display ID3 v1 instead of ID3 v2,so I would see a lot of unreadable scripts in Media Info. I don't know why Songbird give ID3 v1 a higher priority than ID3 v2.

If the mp3 file is with ID3 v2.4 alreay, this situation never happen. But I still wonder why Songbird read ID3 v1 instead of v2.
Thanks for pvh's tip, now I turn off the metadata write function, I should be unable to happen again.
Sorry for my poor English.