#include <Array.au3>
; вариант 1 - строковый
Global $str = "|", $i = 0
Do
$num = Random(1, 20, 1) & "|"
If Not StringInStr($str, "|" & $num) Then
$str &= $num
$i += 1
EndIf
Until $i = 10
$str = StringTrimRight(StringTrimLeft($str, 1), 1)
$array = StringSplit($str, "|", 2)
_ArrayDisplay($array)
; вариант 2 - вероятностный
Global $array[100]
For $i = 0 To 99
$array[$i] = Random(1, 20, 1)
Next
$array = _ArrayUnique($array)
ReDim $array[10]
_ArrayDisplay($array)