In some dialects, the pronunciation of "oirre" and "orra" really are identical, and context is needed to distinguish them. In actual conversation, the context is available, but here in Duolingo it is usually absent. It would be nice if the sentence used here were had "Tha mi a' cluinntinn Anna" or something similar in front of it.
This is a relief to hear - I have been trying this over and over to try and spot the difference. The sound files here https://learngaelic.scot/grammar/greim/gg_using_air_pronoun.jsp also seem to make no distinction. I wonder if native speakers rely on context mainly, or is it possible to tune your ear to hear this?
I listened very carefully several times to oirre and orra before I answered this question. The sound in the sentence was definitely the same sound as orra in your recording and it was not the sound of oirre in its recording. I agree with Bob723588. Are you quite sure the recordings are correct? I can only go by the sound of your recording. This is just confusing.