Why do I get multiple copies of books, and why can't they be deleted?

I have downloaded one book - because ADE is the only software the publisher uses.

I currently have 4 copies in the library - which I cannot delete (dustbin icon on ipad) or remove from library (PC). The PC version tends to stop working/crash if you try to delete more than once in quick succession.

This is extremely annoying to say the least!

Can someone provide a step by step idiot's guide to how to get rid of the unnecessary duplicate copies permanently?