Hello Michael,
sorry if I misunderstand your issue, but before patching these two maps
are you sure that each has a set of cat values strictly distinct from
the other? If a vector feature in map A shares the same cat value as
another feature in map B then after patching these features will be
Michael, Huidae
thats's what I was just about to post... you need to care cats
intervals don't overlap before patching.
With the attached set of 2 vector maps you can have a try, typing :
v.in.ogr input=/your/path/to/map1.gpkg output=map1
v.in.ogr input=/your/path/to/map2.gpkg output=map2
