Problema con generazione password random

[Mizushi]

Provo così, ma la seconda password a volte è incompleta:

function randomKey()
    dim num, wor
    num = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@$%&?*+#-_.:{[]}<>"
        Do Until len( cupon1 ) = 12
            Randomize
            wor = Int( ( 53 * Rnd ) + 1 )
            cupon1 = cupon1 & Mid( num, wor, 1 )
        Loop
    randomKey = cupon1
end function

        for i = 1 to 2 
           r_1 = randomKey
           r_2 = randomKey
        next