duplicate messages

[Bhaskara Marthi]

I just installed offlineimap 6.5.4 on os x and have been running it
for two days.  I've noticed that there are duplicate messages in the
maildir.  For example,

[~/offlineimap/gmail/[Gmail].All Mail/new:] ls -lar | grep 309967
-rw-r--r--      1 bhaskara  staff    285192 Apr 10 12:42
1365622934_3.36127.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,
-rw-r--r--      1 bhaskara  staff    285192 Apr  9 22:33
1365572012_0.60007.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,
-rw-r--r--      1 bhaskara  staff    285192 Apr  9 20:19
1365563963_0.60007.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,
-rw-r--r--      1 bhaskara  staff    285192 Apr  9 14:09
1365541760_0.94849.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,
-rw-r--r--      1 bhaskara  staff    285192 Apr  9 11:32
1365532320_0.94849.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,
-rw-r--r--      1 bhaskara  staff    285192 Apr  7 23:11
1365401517_0.94849.bmm.vicarious,U=309967,FMD5=844bb96d088d057aa1b32ac1fbc67b56:2,

[~/offlineimap/gmail/[Gmail].All Mail/new:] diff
1365622934_3.36127.bmm.vicarious\,U\=309967\,FMD5\=844bb96d088d057aa1b32ac1fbc67b56\:2\,
1365572012_0.60007.
bmm.vicarious\,U\=309967\,FMD5\=844bb96d088d057aa1b32ac1fbc67b56\:2\,

[~/offlineimap/gmail/[Gmail].All Mail/new:]

So in this case we have six messages with that UID, and they are all
identical, as shown by the empty output of the diff.  Is this
expected?  The account is a gmail account, but I'm only backing up the
"All Mail" folder, so the duplicates shouldn't exist, to my
understanding.  I also verified on the server that there's only one
copy of that message.