Merging duplicate references to maintain group membership

I have a database which includes the results of online searches. I have sorted the results of these searches into various groups.  The database includes some duplicate references, which belong to different groups.  Is there a way to merge these duplicate references, so the reference remains in both groups?  Right now, when I do a duplicate search, I can see the duplicate references but if I delete one, I have to manually put the kept reference into all of the groups of which the deleted reference was included in. 

For example, I have two duplicate references, Ref1A and Ref1B.  Ref1A is part of groupA, groupB, and groupC.  Ref1B is part of groupD and groupE.  Is there any way to search for and merge Ref1A and Ref1B, so the resulting Ref1 remains part of all the groups, that is groups A, B, C, D and E?  

One reason that I want to do this is to streamline my database.  Ref1A and Ref1B may both have PDFs attached and it is a waste of memory to store both.  Or, alternatively, Ref1A may have the pdf and Ref1B may not have a PDF, so when I look at Ref1B, I don’t realize I have the PDF elsewhere. 

This process would also help me when I add new searches, so I could just add the results of my search from ovid or ebsco host, and then search for duplicates with what is already in my database. 

Thank you for any hints or tips!