Travelling coincidence

Many years ago (too many now! – 1990) a friend and I were travelling to East Africa to visit a mutual friend of ours and to do some climbing (Mt Kilimanjaro and Mt Kenya). We all knew each other from the save university caving club. Being recent graduates, our flights were cheap and cheerful ones with Aeroflot. The route took us from Heathrow to Nairobi via a change at Moscow. At Heathrow our seat numbers were allocated: we were sat together. At Moscow we had new and different seat allocations which shuffled everyone around the plane, separating existing travelling companions and 1st leg formed new friendships. I and my friend were separated. Early on into the 2nd leg it became apparent that the air stewards were not bothered if people changed seat allocations. So began the 2nd mass passenger shuffle. I and my friend were back sat next to each other in different seat numbers. In a row of three seats we were sat next to a young lady in the window seat who we did not know from the 1st leg. We got chatting and swapping stories. One laughable story we started to tell each other turned out to be very similar. In fact, it turned out to be the same story about the same person, another friend of ours from the caving club. This young lady worked with yet a different mutual former caving club member friend of ours who had told her the story which she had found funny enough to include in her own story repertoire. I have always considered this a remarkable coincidence and despite travelling a lot since have never met a friend of a friend in quite the same way.