PHP crypt function password encoding
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The following code returns the same encrypted password whichever way round. Why and how do we stop this.

    $pwd = 'shits8888';
    $salt = '50153fc193af9';
    
    echo crypt($pwd,$salt)

Obviously something is missing as this is returning the same thing

    $pwd = 'shits8888hjhfgnsdkjf8744884';
    $salt = '50153fc193af9';
    
    echo crypt($pwd,$salt)