How to install SharePoint Designer 2010 and SharePoint Designer 2013 side-by-side?

Hello,

I have Windows 7 32-bit machine and had Office 2010 with SharePoint Designer 2010. Now, I upgraded to Office 2013 and installed SharePoint Designer 2013. Anyway, I still need to have SharePoint Designer 2010 installed side-by-side with SharePoint Designer 2013. Please advise, how to achieve that?

Best regards

Maciej