The hardware compatibility page at https://www.iospirit.com/products/remotebuddy/hardware/#eyetvreceivers has this to say about the matter:

"The Apple® Remote (Aluminium) can be used. With this receiver type, the seperate Select- and Play/Pause-buttons can't be mapped independantly, though."

The reason behind this is that the Aluminum Apple Remote sends a modifier code before the 7th button - and this modifier code is often not recognized correctly by EyeTV receivers. So, if you press the Play button on that remote, it would be seen as either the Play or Select button on a more or less random basis. Since this is the opposite of reliable remote control, the Play button on the Alu Apple Remote is always interpreted as Play button when using EyeTV receivers. That way, you know what action you trigger when you press that button.

This limitation applies only to EyeTV receivers. It does not apply for other, supported IR receivers where Remote Buddy handles the decoding of IR signals itself.

Best regards, 
Felix Schwarz