Don't assume anyone replying to you disagrees. They can be on your side even if there are minor differences between what you said and what they said. If they repeated the exact same thought, there wouldn't be a point to replying at all.
Mostly when I see this, it's more an issue of the person getting angry at a reply didn't actually read or comprehend the reply.
So many times I have seen someone basically repeat the exact same thoughts as a previous post, but used different words to express it and the person they reply to starts attacking them. Like, dude. Did you even read?
It's also worth remembering that is a public discussion. Often times a reply to your comment is not directed at you directly, but to the audience at large.