Using Merchant, Brand, Category and Name Filters with searchExternal.php

Hi Dave,

A while back you modified my PT setup so that I could filter searchExternal results using:

merchant:
category:
brand:
name:

My question is: can I use 2 filters in the same string? An if so, how do I write this?

so for example:

merchant:dixons & brand:panasonic

tried this but it doesn't work
$_GET["q"] = "merchant:dixons brand:panasonic";

thanks,
Neil