diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index bbe2b8bb4af..988b92da75b 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -1992,7 +1992,7 @@ package--find-non-dependencies
 (defun package--save-selected-packages (&optional value)
   "Set and save `package-selected-packages' to VALUE."
   (when value
-    (setq package-selected-packages value))
+    (setq package-selected-packages (delete-dups value)))
   (if after-init-time
       (customize-save-variable 'package-selected-packages package-selected-packages)
     (add-hook 'after-init-hook #'package--save-selected-packages)))