Copying Layer A to Layer B, then saving without losing original Layer A

Is this possible, without copying to another Program and then back?
I had a nice Tine-y Rhodes, that, by only increasing Filter Drive and changing the Instrument Category in Instrument 2, sounds like a blown up Hammond. I'd like to keep them both on the same Program, so I could switch with just a single press of the Edit Layer B button, or even stack them: but if I swap layers, and then try to save, I'll have the old Layer B sound on Layer A instead of my original Tine-y Rhodes; and if I RECALL, I'll have lost the edit into the Hammond.
 Luckily, I can not save anything, and with only two knob turns be back at the Hammond from the EP; but in the interests of learning about this fine and powerful but in some ways limited instrument, and with the possibility of turning them into a 4-voice stack, (or 8 in 16-voice mode), I'm posting this anyway, to benefit from some of the finer minds here. Thanks!
T8, Tempest, OB6, Prophet X. 8DIO Prophet 5 add-on, Sample Packs from Lady Gaia (synth waveforms) and Modulatable.com (Moog One.)