Comment

Tom

I found another possible solution for the problem:
Encapsulate every button in its own form. So instead of
<form action="showRequestVariables">
<button type="submit" name="button1">Button1</button>
<button type="submit" name="button2">Button2</button>
</form>

you write

<form action="showRequestVariables">
<button type="submit" name="button1">Button1</button>
</form>
<form action="showRequestVariables">
<button type="submit" name="button2">Button2</button>
</form>

IE now posts the correct values (at least that worked for me).