I don’t know if you have the resources to do this, but I think that it’ll be better to make Anakin’s voice higher, because his voice in AOTC and in OWK are notably different. Maybe not in all the shots, but in the beginning of the flashback for example, his voice is clearly deeper, and this can contrast with the rest of his scenes in AOTC.
That would honestly be trivially easy but I’m not sure I hear the difference you’re talking about.