Assume that you have configured Microsoft SQL Server 2012 Reporting Services (SSRS 2012) or SSRS 2014 to run in native mode or in SharePoint Integrated mode. When you try to create a subscription for a report that has one or more parameters configured, the SQL queries that contain subscription parameters are sent to the data source engine multiple times if you select Override Report Default for the parameters.
Cumulative Update information
The issue was first fixed in the following cumulative update of SQL Server.
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. We recommend that you download and install the latest cumulative updates for SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.