The change in wording at the end may simply reflect that the form has been changed. All certificates of the newer date might bear that last statement.
The commendation certificate which I received is 95% pre-printed text attesting to how attentive to duty, etc. I was. Only the range of dates covered by the award are unique to my copy. If I requested a replacement certificate, I might see my very generic contribution described in a very different manner with the dates filled in to match the prior certificate.
Thank you William Tell .. that makes more sense to me