Don't worry about it. This is why. There is comment form available at the end of each post your WordPress blog. After the form is completed and submitted, the name and e-mail address of the person making the comment will appear and remain visible to them. Why is that and who else can see it? If another person makes a comment are the details of person leaving a comment before them visible to them?
WordPress.com uses cookies to keep track of commenters so if someone makes a comment on your blog, the next time they come to your blog, unless they have cleared their cookies, WordPress.com will recognize them and complete the details for them. No one else will be able to view those details. The next person who comments will see blank fields. Commenters will not see each other’s details.