If someone asks you the same question twice, don’t embarrass them by answering with precisely the same words. Rescue them from that mortifying moment when they realize, “Whoops, I already asked that.” For example, someone inquires, “What year did you graduate?” You answer, “In 1986.” Forgetting they had asked, later in the conversation, they again pose the question, “What year did you graduate?” Don’t repeat 1986”“. That makes it obvious to one and all that they weren’t listening.
Save their face, (and their friendship,) by answering their repetitive question with different words. This time answer “Ten years ago.” They now happily carry on the conversation oblivious to the fact they had screwed up by asking you twice.
Yes, you are being kind by rescuing them from their embarrassment. But it redounds to your benefit as well. Why? A funny thing happens to people. Even though they’ve made the big blooper, their well deserved humiliation later turns to subconscious resentment of you.