There is no rule against "double posting" as you are describing. Who was the moderator that did this and what was the post?

By making two posts, it makes it easier to read, especially when you are quoting multiple responses. If you make one post that responded to 5 or 6 different people then more likely then not the people you are responding to will either not see that you responded to them or will otherwise ignore your post.

This practice may or may not be post padding, however post padding is not against the rules, making insubstantial posts however is, so as long as each of your posts are not insubstantial and contributes to the conversation then you should be fine.