I have observed this in my past dlds and decided to check. 

One image, for instance, shows 20 dls in "My earnings" page. If I go to the earning details, I get:
Downloads: 20
Downloaded by: 20 members, 0 guests 
Version:
  old and 2006 credits : 3 small, 7 maximum, 0 additional
  2007 credits : 3 small, 4 medium, 0 large, 0 maximum, 0 additional
  subscriptions : 4   but 3+7+2+4+4=21
Downloads history shows 20 entries.

I found that at least a couple of other images (checking the first page only) show this kind of sum error, with differences of 1 or 2 dlds.  But much stranger is the following (which in fact was the reason for checking these stats):

Another image shows 15 dlds in "My earnings" and in the earning details:
Downloads: 13 
Downloaded by: 13 members, 0 guests 
Version:
  old and 2006 credits : 4 small, 1 maximum, 0 additional
  2007 credits : 1 small, 3 medium, 2 large, 0 maximum, 0 additional
  subscriptions : 2   and 4+1+1+3+2+2=13
Downloads history shows 13 entries.

I believe this is some bug in level 2 or 3 image, as I can only find this in images with over 10 dlds (but not all).

Has anyone seen this?

Regards,
Adelaide

I just checked my most popular image and have found the same issue.

It shows a total of 90 downloads, but when I add up each of the "versions" they total 92 sales.

I wonder where the difference is?