How to duplicate lines/regions in Emacs

So, I read a blog post just now on line/region duplication over here and thought I'd give it a try as well.

Here's what I came up with:

(defun duplicate-line-or-region (arg)
  "Duplicates the current region (transient) ARG times, but at
least twice. If none is active, duplicate the current line
instead."
  (interactive "p")
  (let ((times (if (> arg 1) arg 2)))
    (save-excursion
      (if (use-region-p)
          (kill-region (mark) (point))
        (kill-region (point-at-bol) (point-at-bol 2)))
      (dotimes (i times)
        (yank)))))

Arrrrrr! Mono docs! *shakes fist*

I just ran into a Makefile that had a rule like this:

blah.tree blah.zip: Makefile
        mdassembler --ecma ./blah -o blah

Why does this suck? Because it will choke on make -jN and die horribly.

How it should have been written?

blah.zip: blah.tree
blah.tree: Makefile
        mdassembler --ecma ./blah -o blah