The stampings are just stampings and they mean very little. There are manufacturers that will stamp their guns 223 or 5.56 for a variety of reasons. Some manufacturers will stamp 5.56mm as opposed to 223 to eliminate confusion as the consumer has wrongly been told that if they see a "223" stamping anywhere it would be dangerous and irresponsible to fire ANY 5.56mm through the gun. Some manufacturers stamp their 5.56mm (or Wylde's) as "223 Remington" to make it less militaristic and more consumer-minded, this is usually political as there are many countries that strongly regulate ownership, import, and/or export of "military style calibers".
Typically barrel stampings are important (though I'd argue if the rifle is 223/Wylde/5.56 marked it is less so), but receiver markings don't matter at all as various other calibers can typically be used (are often are) with one particular frame or receiver.