My female colleague cannot remember a discussion (dialogue) from a couple days ago or even yesterday, much less the full, exact sentences spoken. She jokes about having sclerosis. I can remember many dialogues from the last couple of years and even further, including the exact sentences – not all the dialogues from my life, but like 80% of those which were interesting, odd, or very funny, or made at least small impact in my life. Is this kind of long memory normal in people? Does it have a name? Thanks.
the cognitive skills of a human population have a great variance. I am more like your friend, with episodic memory below average but semantic memory above average. You seem to have episodic memory above average (I envy you on that, because a large part of our feeling of self identity depends on episodic memory). There are extreme cases of people that remember almost everything they experience or read, or hear. A nice book on the topic is Luria's book "the mind of a mnemonist". It is a short book, and I'm sure you'll find it pretty interesting.
The remembering of specific events is known as Episodic memory, and you can find plenty about it online. It's usually contrasted with Semantic memory, which is generalized knowledge such as that "Paris is the capital of France".
I'm going to leave it to other users, or myself at a later date, to provide additional references/explanation, but those are the terms you're looking for.