Creating a dialog with /dialog -m A B isn't renaming it. The first parameter of the /dialog command is the dialog instance name. The second parameter of the /dialog command is the dialog table name (ie. the name of the dialog layout definition). You can of course have multiple dialogs open that all use the same table. But none of this means anything is renamed.
The OP wants to actually rename existing dialogs without closing and reopening anything in order to account for dialogs that are named after dynamic things (for instance a nickname which might change while a dialog is open). That simply isn't possible using existing commands. You can 'fake' it by storing the dialog's state, closing it, and restoring it with the new name, but that would be a great deal of effort and would probably cause noticeable flicker.
