It could be a coincidence. About half of all 4-digit numbers contain at least one repeated digit. (Of 10000 possible numbers, 10 * 9 * 8 * 7 == 5040 contain four distinct digits.)
$ pins() { seq -f '%04.0f' 0 9999; }
$ pins | egrep -c '(.)\1'
2710
$ pins | egrep -c '(.).*\1'
4960
$