Variable: history-delete-duplicates
history-delete-duplicates is a customizable variable defined in
minibuf.c.
Value
nil
Documentation
Non-nil means to delete duplicates in history.
If set to t when adding a new history element, all previous identical elements are deleted from the history list.
This variable was added, or its default value changed, in Emacs 22.1.
Probably introduced at or before Emacs version 22.1.
Source Code
// Defined in /usr/src/emacs/src/minibuf.c
DEFVAR_BOOL ("history-delete-duplicates", history_delete_duplicates,
doc: /* Non-nil means to delete duplicates in history.
If set to t when adding a new history element, all previous identical
elements are deleted from the history list. */);