I have done this before, what I did was accidentally copied them by selecting the ones I wanted to delete and moved the selection a bit and whammo.. all copies..   So what I would suggest you do is, open the "my picrures" folder and then click View > List.  Then select all the pics (copies) that you want to delete using the ctrl-click method and then after all selected right click and then hold down the shift button and click delete (anytime that you hold down the shift button while clicking delete it will bypass the recycle bin and delete them permanantly).  Goodluck!