проверь

FileCopy("myfile.dll", "myfile.dll.bak");

$sInFile = @ScriptDir & "\myfile.dll"
Local $aFind[7] = [ _
"strin1g", _
"strin2g", _
"strin3g", _
"strin4g", _
"strin5g", _
"strin6g", _
"strin7g"]

$0 = Chr(0) ; Получить Null
$sReplace = $0 & $0 & $0 & $0 & $0 & $0 & $0 ; Типа 7 раз Null

$sOutFile = @ScriptDir & "\myfile.dll.tmp"


_Replace($sInFile, $aFind, $sReplace, $sOutFile)

Func _Replace($sInFile, $aFind, $sReplace, $sOutFile)
    Local $FO, $FR
    $FR = FileRead($sInFile)
    For $i = 0 To UBound($aFind) - 1
        $FR = StringReplace($FR, $aFind[$i], $sReplace, 1)
    Next
    ; $FR = StringRegExpReplace($FR, 'strin[1-7]g', $sReplace) ; Вариант взамен цикла
    $FO = FileOpen($sOutFile, 2)
    FileWrite($FO, $FR)
    FileClose($FO)
EndFunc

FileMove("myfile.dll.tmp", "myfile.dll", 1);