[U-Boot] designing a firmware update mechanism

I have an embedded project using an atmel arm processor, primary bootloader at91BootStrap on NOR to call uboot (and the reset of the system) on NAND.

I am trying to devise a way to partition NAND redundantly, with 2 copies of (uboot + uboot-env + kernel + roofs).

At91bootstrap will have to decide which uboot to start some how. I have not determined this yet, but I think reading something out of the two uboot-env areas might be a good start.

Will I need to compile 2 versions of uboot, differing only in where to look for the uboot-env, or is there another way?

I don't think giving one copy of uboot 2 uboot-env will do the trick.

Could anyone share a firmware update strategy with me that uses uboot, or is that outside the scope of this list?