Recently I have rearranged my library system, wherefore I have now a number of duplicate entries. Each of the references is however assigned to different groups. So:

  1. How can I find out to which group a reference is assigned? Should not there be a field in the reference details where the group (i.e., tags) are listed?

Now, how do I decide which reference to delete and then, to which groups do I have to reasign the remaining reference? 

It would be so great if you could provide a solution for this problem. The best would be a function to just merge both reference copies instead of having to discard one of it. Through the merging process then the group assignments of both refercences should be kept of course! 

Maybe there is. Then please let me know how I can solve it.