Anyway, I measured the key that opens both locks & found the bitting to be "34232" instead of the housing stamped "12133". So the first thing I did was assume my calipers were wrong or misunderstood the process or results and measured 2 more keys with numbers stamped on them. Both keys ( another kwikset & a gatehouse) produced the exact same number which was stamped on each key. So now I'm a little confused & that usually means I've missed something. So I did some more Google-Fu & found lots of really good stuff but I'm still confused & figured I'd call on you all again.
Based on my the above, I'm thinking this has to do with master keying somehow but I'm not really clear on how that actually works. I'm thinking I should have a look at the pin stacks & see if there are any mini-disks in there or not, which would let me know one way or the other unless there is an easier way to tell.
Neither of these locks are in use, so no worries. Also, one thing I learned working on handgun small parts is that it's best to put the whole mess, and your hands, in a large zip-lock bag for disassembly so springy things don't just go away magically. (Don't ask me how I know this)
Thanks for reading and any sage advice or wisdom.