Last month Google came out with two new updates for their Panda algorithm. This is rather uncharacteristic of them as they usually only bring out one update every four to six weeks or so, and in most cases it takes even longer.
The first update for the month is Google Panda 3.7. Google has confirmed that there was a refresh that started to roll out on Friday the 8th of June that affected less than 1% of total queries. Google has said that this update will affect no more than 1% of search queries worldwide.
There was no definite confirmation that this was an actual update, however, Google went straight from update 3.6 to update 3.8 and by the time people started to speculate that this refresh was an actual update, the algorithm was due for one.
Panda update 3.8 started to roll out on Monday the 25th of June. This update was also only a refresh, this means that no algorithm signals were updated. Google simply just ran the algorithm again in order to weed out sites that they believe deserved to be handicapped by the algorithm.
SEO experts can still only speculate why Google released two algorithm updates so close to one another, there was only a two week gap..