WordPress Within an Existing WordPress Installation on IIS 7.5 With Permalinks

On Windows Server 2008 R2 and using web platform installer. Installed WordPress to the root. All is working fine there.

I then created a folder within the root called “SUB” and another one within that called “SITE1”. The URL is therefore https://server.com/SUB/SITE1/

The site works find if permalinks aren’t set. However once they are I get a

HTTP Error 500.52 - URL Rewrite Module

error which says Cannot add duplicate collection entry of type ‘rule’ with unique key attribute ‘name’ set to ‘wordpress’ The content of web.config is as follows

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
            <rule name="wordpress" patternSyntax="Wildcard">
                <match url="*"/>
                    <conditions>
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true"/>
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true"/>
                    </conditions>
                <action type="Rewrite" url="index.php"/>
            </rule></rules>
    </rewrite>
  </system.webServer>
</configuration>

Any idea how to get this 2nd install working with permalinks enabled? I’ve tried putting the sub site as an application but nothing

I’ve added <remove name="wordpress" /> to the web.config file but when I visit any post/page it shows the 404 error from the WordPress install in the root

Thanks in advance

JJ