>1. define second Library with same private category but a 'new' scratch
>category,  that's pointing to original library:  (Name changed only from
>LIB to L2B.)
>
>def libr 3494L2b libt=349x device=/dev/lmcp0 privatecat=400
> scratchcat=402   ( 401 is the original scratch category)

As the model number implies, the 3494 was originally introduced to hold
3490 tapes.  3590s are an addition, but the 3490 concept remains.
Refer to the Admin Ref on DEFine LIBRary.  It explains that the
SCRATCHCATegory you define is for the now-fictitious 3490 tapes,
and that SCRATCHCATegory+1 is implied for 3590s.  Your original library
definition had SCRATCHCATegory=401, with 402 implied for 3590s.  Your
new definition conflicts with that.
  Richard Sims, BU