Ay is a vocative particle; ayy in ayy ṭālibin ḥaḍara is an interrogative noun. They are not interchangeable.
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Ay versus Ayy
Vocative Particles: Five Forms, Uses and Parsing
Ay is a vocative particle; ayy in ayy ṭālibin ḥaḍara is an interrogative noun. They are not interchangeable.