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Will installing windows 10 insider preview on another partition affect my old windows 7 recovery?
Windows 10 with old recover
While playing in Preview verions, it's best to do it in VM.
Yeah do it in a VM.
Normally, it shouldn't. But still safer to use VMs.
D
Or, you can boot the VHD directly. 
Do convert to VHD if from vmware. Add the VHD via easyBCD, and you're done.
Do convert to VHD if from vmware. Add the VHD via easyBCD, and you're done.