How can I avoid that in the original post of a team discussion my picture shows up instead of original author after editing the metadata?

Hi,

I sometimes have to edit metadata in discussion board posts (SP2010) of my clients but the problem is that instead of showing the person who posted the question/ contribution now my picture shows up and instead of showing the posting date, it changes to my editing date. The editing is usually very minor but users get confused if they see my picture there instead of the original person in the discussion thread view. The list is still sorted by "posted by" but shows the picture of the person who edited the post.

How can I avoid this? How can I fix this for existing edited items?