Upload & Sell: Off
Older versions stay current versions get written over of all the plug-ins not just HDR Efex1. On both my PC and Mac the current versions did not duplicate and on PC HDR Efex1 stayed.
Josh Haftel from Nik support wrote on Google+
+Jan Kabili The Nik Collection will work just fine with previous products like Color Efex Pro 3, Silver Efex Pro 1, HDR Efex Pro 1, etc. If you still find value in those older products, please keep them installed. The Nik Collection will automatically upgrade only the current products, and will leave those older products installed. If you don't want them, visit the support site for uninstall instructions: support.google.com/nikcollection
+Mark F The Nik Collection contains all of the Nik plug-ins. The installer will replace the old Nik Software versions of Color Efex Pro 4, HDR Efex Pro 2, Silver Efex Pro 2, Viveza 2, Sharpener Pro 3, and Dfine 2. It will leave older products alone, like Color Efex Pro 3, Silver Efex Pro 1, HDR Efex Pro 1, etc. You really don't want two copies of the same product on your system