Wrong commenter name/email are displayed in comment form

Dear all

I have come across a very weird problem in a blog I support for a friend of mine.
The last 1-1.5 months, there are 3 distinct cases where commenters have reported that they see wrong information for the comment author name and email fields when they are trying to post a new comment.

The wrong information is not random but belongs to other commenters of the site (e.g. a commenter with name let’s say ‘UserA’ and email ‘EmailA’ sees ‘UserB’ and ‘EmailB’ where both ‘UserB’ and ‘EmailB’ belong to a different -valid- commenter that visits the site).

The problem does not happen frequently enough so I cannot reproduce it at the moment. (The site has a few hundreds of commenters and an average of 200-300 comments per post so the error’s ratio is rather low).

I know that the comment form fields are set via cookies when a commenter posts a new comment however the fact that the wrong information is a valid name and email of another commenter, suggests that this info comes from the database somehow which I find it very strange.

So I would like to ask the following to the community and especially to wordpress developers:
1) does such an issue sound familiar for worpress 4.4.2 or previous versions? Since the issue started to appear about the time wordpress 4.4 was released I was wondering if any relevant issues existed which are now perhaps fixed in 4.4.2?
2) what would be a suggested approach to track the issue down in a live site? I have studied the way wordpress creates a new comment and it fires quite an amount of filter and action events so theoritically either wordpress or any plugin could cause this. From the code I have reviewed though everything seems to be ok.

If there are any ideas/thoughts on what could be the cause of such behaviour I would highly appreciate it if you share them

Best regards