Android is Linux. There are some dual boot phones with Android / WM. But it's not common.
Linux is the core of Android operating system. Android is the user interface built on top of it. Another UI built on top of Linux core and targeted to be used on mobile phones is MeeGo, which is developed by Intel (Nokia used to develop it too, before M$ corrupted them to switch to Windows Phone 7). The only phones I know that can run MeeGo are Nokia N900 and Nexus S.
I'm afraid you're probably confusing something. What did you mean by "dual-bootable (linux/droid)"?