How to re-download Yosemite for creating second partition? I have a paid Apple Developer account, and want to create a Beta-Partition with Yosemite. 

I thought the way is pretty straight forward:


Downloading Yosemite
Install it
Choose second partition


But I cannot even download it from the App Store. I am on OS X 10.10.2 and want to try 10.10.3.



How can I create a Beta Partition after already having 10.10.2 installed?

If I boot in recovery mode and re-download Yosemite, will it delete my hard drive? Can I re-download and then choose my second partition?
When you go to the purchases-tab OS X Yosemite should show up with a Download button. When you click it it asks you if you want to re-download it event though it is installed. (Downloading from the purchases tab is different from downloading from the product page I believe.)