1.5 times more visitors since update to piwik 1.11.1

Since the update on piwik 1.11.1 we track 1.5 times more visitors. Its actually the factor for all couters, its not that the average action per visit would be lower, so that the visitors counted might have been split cause they havent been recognized properly. Our own IPs have been excluded and still are, which we thought at first might be the problem. Before the update the download URL was only our own domain, after it also lists all kind of domains where files are linked from our website. If I count them together, they stand to the downloads from just our domain at a rate of something like 1.1 or 1.2. So, now since weeks we are puzzled - any idea here, what we are missing?
Thanks in advance!