When you mention solution i think you have misunderstood. I am just working with report designer at the moment. No visual studio involved.
What I meant is we can run/execute/use visual studio 2010 and 2013 simultaneously on the same computer or SQL 2008 and SQL 2012, why doesn't report designer allow that? I have to close one to open the other.
My main issue is because when I installed telerik Q3 2013, I opened the reports I made on telerik Q1 2013 and saved it. These reports just does not work with Q1 2013 Telerik reporting anymore. There is no way to restore the report to Q1 2013 at the moment because there is no upgrade wizard on Q3 nor is there save as older telerik reporting version. So if I can open both Q1 and Q3 Telerik report designer applications, i can just restore everything manually eg, copy and paste.