I had the same problem with German and Chinese pages. I just keep the original input and instead add an appropriate charset header in the HTML head. For the German pages, I use:

<meta http-equiv="Content-Type" 
      content="text/html; charset=iso-8859-1">
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For the Chinese pages, I use utf8. I believe all the characters used in Dutch should be in iso-8859-1, so you could just use that one.