What could be the cause of these anomalies?
User-agents are very different:
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0) Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB7.5; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Mozilla/5.0 (Windows NT 5.1; rv:22.0) Gecko/20100101 Firefox/22.0
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; .NET4.0C; .NET4.0E)
Opera/9.80 (Series 60; Opera Mini/7.1.32448/30.3442; U; EN) Presto/2.8.119 Version/11.10
Grails 2.2.0 / JQuery 1.7.2