What is the ruling on a second divorce if it was pronounced with the words, "You are divorced, you are divorced, you are divorced," with the intention of irrevocability, then the intention changed during the 'iddah (waiting period)?

The intention to reconcile at the time of uttering the divorce has no bearing on the legal ruling. If you utter "You are divorced, you are divorced" to a wife with whom you have consummated the marriage, whether you intended two divorces or nothing at all, two divorces are incumbent upon you. If you intended to inform your wife or to initiate the divorce with the first utterance only, and made what followed an affirmation, then one divorce is incumbent upon you. As for repeating "You are divorced thrice," if you intended affirmation and initiated the divorce with the first utterance only, then one divorce is incumbent upon you, and you can take her back before her waiting period ends, provided you have not divorced her twice before. However, if you intended to initiate divorce with the second or third utterance, then she becomes unlawful to you until she marries another man. If the marriage has not been consummated, then she becomes irrevocably divorced from you with the first utterance only, and her return is not valid except with a new contract.