I have been developing with SPServices extensively for 3 years now and I'm certain that has never happened to me or any of my users. Once an item is deleted from a list and moved to the Recycle Bin, it is not accessible by GetListItems or any other web service call that I'm aware of. When you say "even the removed ones", have you verified those items are actually in the recycle bin at the time the web service is called? Is it possible you have duplicate records?
Geoff
Geoff