Clarify if children of Protocol are expected to be unique

[petrvanekrobe]

The Protocol children section does not explicitly mention amount of allowed children/that children are unique, so technically this is valid by today's spec:

    <Protocols>
        <Art-Net>
            <Map Key="0" Value="1" />
            <Map Key="1" Value="2" />
        </Art-Net>
        <Art-Net>
            <Map Key="0" Value="3" />
            <Map Key="2" Value="1" />
        </Art-Net>
        <CITP />
      <FTRDM DeviceModelID="0x6" ManufacturerID="0x5253">
        <SoftwareVersionID Value="0x1">
          <DMXPersonality DMXMode="Mode 5 - 8bit inverted" Value="0x5"/>
          <DMXPersonality DMXMode="Mode 2 - 16 bit normal" Value="0x2"/>
          <DMXPersonality DMXMode="Mode 1 - 8bit normal" Value="0x1"/>
          <DMXPersonality DMXMode="Mode 3 - 8bit extended" Value="0x3"/>
          <DMXPersonality DMXMode="Mode 4 - 16 bit extended" Value="0x4"/>
        </SoftwareVersionID>
      </FTRDM>

      <FTRDM DeviceModelID="0x7" ManufacturerID="0x5352">
        <SoftwareVersionID Value="0x1">
          <DMXPersonality DMXMode="Mode 5 - 8bit inverted" Value="0x2"/>
          <DMXPersonality DMXMode="Mode 2 - 16 bit normal" Value="0x5"/>
          <DMXPersonality DMXMode="Mode 1 - 8bit normal" Value="0x1"/>
          <DMXPersonality DMXMode="Mode 3 - 8bit extended" Value="0x3"/>
          <DMXPersonality DMXMode="Mode 4 - 16 bit extended" Value="0x4"/>
        </SoftwareVersionID>
      </FTRDM>
    </Protocols>