Eric,
You have asked this already on the German Forum site,
and Memmo provided a sophisticated answer to you.
You can use the second door lock with the same key as for the other locks only if the key blank fits your additional (second) door lock.
If it doesn't go into it (without turning) - then not, then you need for that one an individual key.
The door handles themselves are identical for left and right hand side - independent from this little casted number "1" or "2" - that isn't of importance.
Only make sure that your door handles (and internals) were made by YMOS but not HUF because the parts look similar but are not interchangeable.
As far as I can see this your door handles are correct.
So, relax...
Achim