2 SSRS Instances, one in native mode and one in sharepoint integrated mode with PowerPivot and PowerView on same server Wanted to know if I can have two SSRS instances on the same server, one in native mode and one in SharePoint integrated mode. 

I have one SSRS instance in native mode on a SQL server default instance (mssqlserver). I added the second SSRS PowerPivot instance to get PowerPivot/PowerView in SharePoint, but realized I have to have an SSRS instance in integrated mode as well to get this feature to work. When trying to add this SSRS instance in integrated mode to the PowerPivot SQL  instance, it only gives me the option for native mode and integrated mode is grayed out. 

I am running SQL 2012 SP2 enterprise on the same server as SharePoint 2013 enterprise. I wanted to have both because our ERP utilizes the SSRS native mode in their reports and you can set security through the ERP and have the users view the reports within the ERP system. If this cannot be done, we will have to take all the reports and dashboards out of the ERP and manage them separately with the windows security in SharePoint.
So after messing with this off and on for a while I figured it out. It is possible. All this was done on one server with SharePoint 2013 enterprise and SQL Server 2012 Enterprise with SP2.  

I have a default SQL server instance with all features selected, specifically the shared features "Reporting Services - Sharepoint" and "Reporting Services Add-in for Sharepoint Products". Then you have to run through the installer again and add a new instance. Then select "SQL Server PowerPivot for Sharepoint" (relational database check box at this point was not needed). After you do this you have to activate this feature in SharePoint. Here is a blog on how to do the PowerPivot setup.

Make sure this instance is at the same service pack level once you install it. After this I followed this walk-through, starting at step 2, to enable SSRS in SharePoint.

That is pretty much it. I now have a native SSRS site and SharePoint integrated SSRS site as well as PowerPivot/PowerView all on the same server. All databases are on the default instance. I only have SSAS installed for the PowerPivot instance and that is it.