Repetition of comments is a known bug - the same comments show in all blog pages when viewing them inside the Wix editor in Preview mode.
We are working with Wix to fix this issue.
Please be assured that it does not affect the published site, so in the published site you should see different comments on each blog post.
If, nevertheless, the comments repeat in all Comments boxes in Publish mode as well, please write me again and we will fix the problem.
Thanks
:)
Nurit