Please consider having the following JSON for LLD:

[
   {
       "{#TYPE}": "A",
       "{#DATA}": 1
   },
   {
       "{#TYPE}": "B",
       "{#DATA}": 1
   },
   {
       "{#TYPE}": "A",
       "{#DATA}": 2
   },
   {
       "{#TYPE}": "B",
       "{#DATA}": 2
   }
]

You can look at this as at two sets of objects (objects A and objects B), each having two values (1 and 2):

• A.1
• B.1
• A.2
• B.2

There are two item prototypes assigned to this LLD rule:

• trap.a{#DATA}
• trap.b{#DATA}

At this point, this configuration would cause an error as there will be item duplicates, so I add overrides:

• TypeA

  Filter: {#TYPE} mathes A
  Operations: Item prototype contains trap.b
  Discover: No
  

• TypeB

  Filter: {#TYPE} mathes B
  Operations: Item prototype contains trap.a
  Discover: No
  

All 4 items are discovered, but two of them are lost (trap.a ones) right away and I have an error about item duplicates on discovery.