D600 copy from Slot 2 to 1
the D800 has a copy images option in the playback menu, which i've never even seen before your question piqued my curiosity. i don't know if the D600 also supports this function, or whether it will work as you desire. still, at a quick glance it looked promising. until now, i probably would've answered no to your question...
|Steamin' Mad by ahrensjt|
from Angered Subjects (Street Photography)
|Smile by Olymguy|
from Ultra Asian Indian Female Faces
|Space Shuttle Cockpit- by vbuhay|
from Aircraft Control Stick