如何防止使用这个UNION select(或其他方法)复制

I am trying to get a certain set of results with a UNION SELECT, and I am having trouble figuring out how to limit my results accordingly. Essentially I have objects that I am returning and displaying in the form of several of their attributes. One of those attributes is a comment that can be made on the object. Some have comments on them, and some do not. I want to display all that have comments as well as all that do not have comments. The problem I am running into: My first SELECT is returning all of the instances with comments just fine, but my second SELECT which is meant to return the instances without comments, not only does that, but also returns a duplicate instance of the previous, but without a comment. So in the end I have all instances where there is no comment, and if there is a comment, I get in instance with the comment and a duplicate but without the comment. I have pasted my code below, but if you feel there is a better way of doing this other than using a union select, your enlightenment is much appreciated.I am trying to get a certain set of results wit