two slices, copy one slice to another?

[Steve P.]

Is there a trick to copying one working system from a slice to another 
slice?

What I envision is two slices:
    /dev/ad0s1 - one complete install
    /dev/ad0s2  - copy of first install, via dump restore. (Is this 
where I screwed up?)

    I tried this, but upon reboot, I could see both installs. I was given a
    choice of the two, but F2 only booted the first install.
    What is the trick?
    Thanks.
    Steve.