Originally Posted by cklammer
May I ask: What is the plan if an ePub does not have a valid identifier resp. the identifier is not set or set to zero/null?
In this case it will happen, what happens in the moment: if you load the epub again, a second entry will be added to the library page.
I've already checked many epubs. Even the worst formatted have got an identifier, so I'm pretty sure, that this happens only very rarely