5 User:
- A
- B
- C
- D
- E

<?php
$varianten = array(
'A-B',
'A-C',
'A-D',
'A-E',
'B-C',
'B-D',
'B-E',
'C-D',
'C-E',
'D-E',
);

shuffle($varianten);
foreach ($varianten as $variante) {
    echo $variante . '<br />';
}
?>