<configSections>
  <sectionGroup name="Gruppo1">
    <section name="Sezione1" type="System.Configuration.NameValueSectionHandler, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    <section name="Sezione2" type="System.Configuration.NameValueSectionHandler, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
  </sectionGroup>
</configSections>

<connectionStrings>
  <add name="Conn" connectionString="..."></add>
</connectionStrings>

<Gruppo1>
  <Sezione1>
    <add key="Chiave1" value="100" />
          <add key="Chiave2" value="Prova" />
  </Sezione1>
  <Sezione2>
    <add key="Chiave1" value="200" />
  </Sezione2>
</Gruppo1>