When commenting on a Working Copy and then checking-in, those comments are copied across to the source node and the topic is suffixed with the previous version number.
e.g. You have content at v1.2, check it out, add comments, check-in to create v1.3
The topics owned by the content are now:
The posts in the Comments (1.2) topic lose their original commenter property - they all appear to be posted form the user checking-in the content.