Imagecache creates multiple copies of same image

From my experience, that behavior occurs when you upload the same image on a different node ( ie create a node using image.jpg, then create another node using the same image.jpg file ). When imagefield finds the filename in use, it creates a different one.

Much more information is required to reply to this question in full -- such as :
* what fields are you using? ( imagefield, upload, image) ?
* when you say "deleted from the database" how do you mean? if you manually delete the record, Drupal is not aware of the file anymore, and thus will not do anything with it. Files are automatically deleted when their associated nodes are deleted ( eg if you have a node with an imagefield, when you delete the node the relevant images will be deleted as well ).
* you mentioned imagecache -- do the multiple copies occur within the imagecache directories ( myfilesdir/imagecache/mypreset/ )?

I'm afraid it's much more likely to be a bug in your setup/configuration, since a ton of people (me included) do not experience this problem.