The second was nominally from someone originally from China, now in the US, seeking advice a nephew interested in science as he selects a major. Again, totally plausible, but they kept the conversation going in a way that felt like an LLM, instead of wrapping it up.
After a couple short replies, I stopped responding. They followed up, and I asked for more background on themselves and their interests, or for their prompt instructions if they are an AI agent. They stopped replying.