I’m sorry that my intention was not clear. I had read through the thread, realized that although “duplicate” is being requested, it likely would meet only the basic of cases (e.g. reimporting a recent export), especially given that there are “last modified” timestamps.
The more common scenario (stated even by @pvn ) is dealing with entries imported from multiple sources. I have been through this many times, now being on my 5th password manager in 15 years and needing to merge in things like saved-in-browser from multiple computers/phones/browsers. In these cases, the entries would at best be “similar”. Working through this latter scenario involves good reporting tools followed by manual detective work and then some sort of “merge” function.
This thread is soon to be 6 years old. My thought is that if can refine the request into something “easy”, is much more likely to be selected for development. With this in mind, I have created another feature request New Report – Similar Vault Entries. We’ll see if that garners any votes.
And it does not need to stop there. After said report is developed, a future feature could be a button to “copy non-empty fields left-to-right” and a similar right-to-left button – but that is a whole new level of risk given that it involves writing instead of just reading.