When you are doing a second round review, do you read other reviewers' comments? Why? It seems to me that all I need to do is seeing whether the author/s satisfied my comments and whether I find any more problems in the current version of their manuscript.
I do read the other reports, and other reviewers should too. A few reasons:
- If the editor has an author's response letter and two reviews, and the three documents say different things, then the editor will be very confused. If I see the other reviewer and the author disagree, then I try to be a tie-breaker to help the editor.
- Authors are not in a place where they can convincingly say the other reviewer is wrong. If I see that the other reviewer has made a mistake, I can point it out much more effectively than the authors because I am a neutral party. Ideally, editors would be able to do this, but they have limited time.
- By reading other reviewers' comments, I can learn to be a better reviewer.
It is probably best to be as informed as possible at that stage. There is likely no need to repeat comments of others. It might also inform you of things you missed.
However, it does reduce the independence of reviews. If that is important to you, the journal, or the field, you should probably avoid it and deal exclusively with the paper itself.
So, the answer is, it depends. But if you have been sent those reviews by the editor, they may expect you to read them.
Tangential, but I'm guessing that you'll be interested: it is pretty rare for reviewers to explicitly refer to another reviewer's report in their comments. "The authors have not addressed my comments #1, #5 and #9" is very common; "the authors have not addressed the comments #2 and #4 by the other reviewer" is not.
That said, this does not mean the reviewer is not looking at another reviewer's report - there are reasons to do so, e.g. if the paper changes in a way the first reviewer did not like but was requested by a second reviewer, or they might just be curious what others thought about the paper. However, if the reviewers are doing this, they don't indicate it explicitly.
Different people have different ways of looking at things. In my experience, the issues that different reviewers raise are rarely overlapping completely, and sometimes even not at all. I think this is one of the key reasons why there are multiple reviewers in the first place.
Looking at the comments of the other reviewers will give you the opportunity to look at the paper through someone elses eyes, someone with a different education, different experiences and different methodology. By observing and analyzing what shortcomings others have found that yourself have "overlooked" or better, not perceived as such, you will learn a more holistic approach to reviewing and a better idea of what others - and not only yourself - need to find a paper well structured, interestig and understandable.
I always found it very beneficial to look at the other's commments for that reason, and I strongly believe doing so will make you both a better reviewer and will also enhance your own writing and research skills.