I just updated to the version of the lyrics plugin in lucid-proposed (banshee-extension-lyrics 1.6.1-1ubuntu1~lucid2) and enabled it.  Although I haven't heard any distortion yet, there is still a change in the md5 sum (although could this change be due to automatic downloading of album art?).  This was done after freshly copying my backup (from my Downloads folder) to my main Music folder.  The md5sums match:
jonathan@jonathan-laptop:~/Music/Amazon MP3/Florence + The Machine/Lungs$ md5sum 09*
00da0f56c209d65ec25fe2397c088a53  09 - Cosmic Love.mp3
jonathan@jonathan-laptop:~/Downloads/Florence + The Machine/Lungs$ md5sum 09*
00da0f56c209d65ec25fe2397c088a53  09 - Cosmic Love.mp3

Now this was done after playing the song in Banshee with the lyrics plugin enabled.  They don't match:
jonathan@jonathan-laptop:~/Music/Amazon MP3/Florence + The Machine/Lungs$ md5sum 09*
00da0f56c209d65ec25fe2397c088a53  09 - Cosmic Love.mp3
jonathan@jonathan-laptop:~/Music/Amazon MP3/Florence + The Machine/Lungs$ md5sum 09*
dd0015cb90b46cf1d62fab700c683428  09 - Cosmic Love.mp3

I also compared the id3 tags as described above by Peter Weissgerber.  You'll see they've still been edited:
jonathan@jonathan-laptop:~/Downloads/Florence + The Machine/Lungs$ id3v2 -l 09\ -\ Cosmic\ Love.mp3
id3v1 tag info for 09 - Cosmic Love.mp3:
Title  : Cosmic Love                     Artist: Florence + The Machine        
Album  : Lungs                           Year: 2009, Genre: Alternative (20)
Comment: Amazon.com Song ID: 21195894    Track: 9
id3v2 tag info for 09 - Cosmic Love.mp3:
TCOM (Composer): Florence Welch
TIT2 (Title/songname/content description): Cosmic Love
TCOP (Copyright message): (C) 2009 Universal Island Records Ltd. A Universal Music Company.
TCON (Content type): Alternative Rock (255)
TPE1 (Lead performer(s)/Soloist(s)): Florence + The Machine
TPE3 (Conductor/performer refinement): 
TALB (Album/Movie/Show title): Lungs
COMM (Comments): ()[eng]: Amazon.com Song ID: 211958944
TRCK (Track number/Position in set): 9/13
APIC (Attached picture): ()[, 3]: image/jpeg, 77143 bytes
TPE2 (Band/orchestra/accompaniment): Florence + The Machine
TPOS (Part of a set): 1/1
TYER (Year): 2009

jonathan@jonathan-laptop:~/Music/Amazon MP3/Florence + The Machine/Lungs$ id3v2 -l 09\ -\ Cosmic\ Love.mp3
id3v1 tag info for 09 - Cosmic Love.mp3:
Title  : Cosmic Love                     Artist: Florence + The Machine        
Album  : Lungs                           Year: 2009, Genre: Alt. Rock (40)
Comment: Amazon.com Song ID: 21195894    Track: 9
id3v2 tag info for 09 - Cosmic Love.mp3:
TCOM (Composer): Florence Welch
TIT2 (Title/songname/content description): Cosmic Love
TCOP (Copyright message): (C) 2009 Universal Island Records Ltd. A Universal Music Company.
TCON (Content type): Alt. Rock (40)
TPE1 (Lead performer(s)/Soloist(s)): Florence + The Machine
TALB (Album/Movie/Show title): Lungs
COMM (Comments): ()[eng]: Amazon.com Song ID: 211958944
TRCK (Track number/Position in set): 9/13
APIC (Attached picture): ()[, 3]: image/jpeg, 77143 bytes
TPE2 (Band/orchestra/accompaniment): Florence + The Machine
TPOS (Part of a set): 1/1
TYER (Year): 2009
USLT (Unsynchronized lyric/text transcription): ()[eng]: 
A falling star fell from your heart and landed in my eyes
I screamed aloud, as it tore through them, and now it's left me blind
The stars, the moon, they have all been blown out
You left me in the dark
No dawn, no day, I'm always in this twilight
In the shadow of your heart
And in the dark, I can hear your heartbeat
I tried to find the sound
But then it stopped, and I was in the darkness,
So darkness I became
The stars, the moon, they have all been blown out
You left me in the dark
No dawn, no day, I'm always in this twilight
In the shadow of your heart
I took the stars from our eyes, and then I made a map
And knew that somehow I could find my way back
Then I heard your heart beating, you were in the darkness too
So I stayed in the darkness with you
The stars, the moon, they have all been blown out
You left me in the dark
No dawn, no day, I'm always in this twilight
In the shadow of your heart
The stars, the moon, they have all been blown out
You left me in the dark
No dawn, no day, I'm always in this twilight
In the shadow of your heart
 

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