Google AdSense has paid a publisher twice as much in December, so they decided to apologize to the publisher and withhold the funds from their January check. A WebmasterWorld thread has the story from this publisher.
The publisher said:
I checked that I had ben paid the other day and thought did I really earn that much in December but didn't think any more about it.
Have just received an email from Google Ireland saying they paid me double and they will take the extra amount off the next payment - oh well!
We have seen reports of duplicate AdSense checks going out to publishers before, but never a case of where a publisher received twice as much as they should have in a direct deposit or on a single check. In any event, the publisher is not upset - since Google is letting the publisher hold the funds an extra month early.
There were two other publishers who claimed they received twice as much in December. Both expect not to get paid in January. One said:
I got a double payment too for December, but I wasn't going to say anything in the hope that it passed through the system. No such luck. At least I now have the next month's payment even before I earned it.
I am surprised I did not hear about the over payments earlier, I guess either publishers did not notice or they didn't want anyone to know.
Forum discussion at WebmasterWorld.