Say you have an LDAP type account, and you use your email/password pair under that account across many websites, because those different domains actually all reference the same back-end directory. You've built up a couple dozen entries for "different" sites that use that account, such that when you change the LDAP password, you have to then change the password under all those different entries.
Currently 1Pass will warn you about your "re-used" password. But it has no way, as far as I can tell, to tell it, "No, I'm not re-using it, it's really the same password." You could manually go through and copy the site identities from each alternate, but it would be nice if there were actually a "merge" process that you could start from the menus (perhaps under Item), which gets offered when duplicate password strings are detected. Launch a dialog box where the items that have the shared password are listed (or allow the user to select a set of items and launch the box). The box has three segments, with the list of items at left, the new post-merge entry at right, and details of the currently selected item in the middle. You select an item, pick one to be the "master" version that pre-populates the post-merge version, and then it automatically copies in additional entries for certain fields (websites, notes, maybe custom fields), and then you can click through the list of pre-merge entries to inspect details, and each field that hasn't already been merged has Add and Overwrite options. Then you click into the right pane and make any final changes, then hit a MERGE button at lower right to end the process, toss all the old items in the trash, and create the new one.
1Password Version: 7.6.780
Extension Version: 184.108.40.206
OS Version: Not Provided
Sync Type: Not Provided