In (1), the underlined part must modify "two incidents". It cannot modify "He talked about two incidents". (2) is ambiguous.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Anonymous I believe his talking about them happened two days ago is the essence of sentence 1 and the underlined part "which happened two days ago" modifies that.If that is the intention then the sentence is poorly written, and not really understandable. Unfortunately I cannot at the moment come up with a good explanation of why it doesn't work in that