Unquestionably, there is irony in the responses of Rainsford, both to Whitney and to General Zaroff. For, unknown to Rainsford, his developing feelings later in the story contradict both of his statements to the Whitney and Zaroff.
After he himself becomes "an animal at bay," Rainsford understands what he negated in his conversation with Whitney in the exposition of "The Most Dangerous Game." For, as a hunted "animal at bay" in a tree waiting for the hunter, General Zaroff to discover him, Rainsford comes to know the icy fear of the jaguar, whose feelings he has dismissed earlier in the story. Then, at the story's end, Rainsford again contradicts a statement of his own made at dinner with Zaroff when he rebuffs the general's remarks about hunting men, declaring that there was no excuse for killing another human being outside of wartime. Having escaped into the sea, Rainsford appears in Zaroff's bedroom as the general prepares to retire for the night. They fight a duel with swords and Rainsford, who has decared that hunting another man is reprehensible, slays his foe without remorse: "He had never slept in a better bed," Rainsford decides. He has become the hunter of men, a hunter with no sympathy for the hunted.
If we compare those two conversations, they have definite similarities. Both conversations are about hunting. More specifically, both conversations are about the thrill that the hunter gets from hunting a dangerous animal. Here is a bit from the Rainsford and Whitney conversation.
"We should have some good hunting up the Amazon. Great sport, hunting."
"The best sport in the world," agreed Rainsford.
The quote shows that both men are excited to begin hunting the jaguars. Later, Rainsford's conversation with Zaroff is also about the thrill of hunting a dangerous animal.
"I'll wager you'll forget your notions when you go hunting with me. You've a genuine new thrill in store for you, Mr. Rainsford."
The conversations are also similar in their division of types of people. Rainsford tells Whitney that there are two classes in the world. Rainsford says that there are hunters and huntees. What's great about Rainsford's comment is that Whitney and readers will likely apply "huntees" to humans in this context. Whether or not Rainsford means that is questionable, but it does foreshadow his conversation with Zaroff. Zaroff also believes that the hunter and huntee class distinction exists. He uses that distinction to help justify why hunting humans is okay. Zaroff uses slightly different words to identify the class distinction, but the distinction is the same.
"Life is for the strong, to be lived by the strong, and, if needs be, taken by the strong. The weak of the world were put here to give the strong pleasure. I am strong. Why should I not use my gift? If I wish to hunt, why should I not?"
Regarding the topic of hunting, Zaroff and Rainsford have very similar opinions. That's probably why the two conversations are eerily similar. The main difference is Rainsford's role in the conversation. In the first conversation, it is Whitney that expresses compassion toward the feelings of the prey. In the second conversation, that position is taken by Rainsford.