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Actually, it depends on whether they release DP2 as a full Installer, instead of just an update pkg like they did with most Yosemite DP updates. If it's just an update pkg, you may have to install DP1 first. I decided to clean-install Yosemite DP4 last year, had to install DP1, update to DP2 → DP3 → finally DP4. Pain in the a**.
 
Apple usually do not release full installers for betas, so you have to install the first beta and install each beta successively.
 
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