This hasn't personally happened to me.
Another person I know got totally karma bombed by someone last night, "Thegateway" in this instance. We quickly scanned through his posts and got him bumped back up to scholar but that in itself was a little freaky.
How hard would it be to make it so the most possible influence a single person can have on your overall karma is .01?
In reality it wouldn't change much, but it would defiently limit the impact of pissing off the wrong people.
I also wonder how many specific people would loose Sage status if this was applied retroactivly. I really don't care about any of that, it just sucks when someone who has been with us awhile looses scholar cause of one bad night.
On the subject of double posts..
When someone makes a post, can there be a hidden form item with a timestamp value in it? The idea is when someone hits reload, or tries to submit a post multiple times cause the server lagged, it only gets added once. The system sees the user tried to make two posts with the same timestamp and rejects all but the first.