Cypher query returns duplicated results - neo4j

Question

I have the following graph setup:
start root=node(0)
create (F {name:'FRAME'}), (I {name: 'INTERACTION'}), (A {name: 'A'}), (B {name: 'B'}),
root-[:ROOT]->F, F-[:FRAME_INTERACTION]->I, I-[:INTERACTION_ACTOR]->A, I-[:INTERACTION_ACTOR]->B
And the following query returns duplicated results:
START actor=node:node_auto_index(name='A')
MATCH actor<-[:INTERACTION_ACTOR]-interaction-[:INTERACTION_ACTOR]->actor2,
frame-[:FRAME_INTERACTION]->interaction
RETURN frame, interaction
Query Results
+-----------------------------------------------------+
| frame | interaction |
+-----------------------------------------------------+
| Node[1]{name:"FRAME"} | Node[2]{name:"INTERACTION"} |
| Node[1]{name:"FRAME"} | Node[2]{name:"INTERACTION"} |
+-----------------------------------------------------+
2 rows
52 ms
Even if I add one more start node trying to limit the results, I have the same:
START actor=node:node_auto_index(name='A'), frame=node:node_auto_index(name='FRAME')
MATCH actor<-[:INTERACTION_ACTOR]-interaction-[:INTERACTION_ACTOR]->actor2,
frame-[:FRAME_INTERACTION]->interaction
RETURN frame, interaction
I would like to understand why the query returns duplicated results.
I know that it is possible to return unique results by using distinct, but is it possible to change the query in order to return only one result by matching path, without applying an additional operation (distinct)?
(setup and query can be tested at http://console.neo4j.org/?id=q2e0ay)

Answer 1

If you add actor2 to your return list you'll see what the problem is:
frame interaction actor actor2
(7 {name:"FRAME"}) (8 {name:"INTERACTION"}) (9 {name:"A"}) (9 {name:"A"})
(7 {name:"FRAME"}) (8 {name:"INTERACTION"}) (9 {name:"A"}) (10 {name:"B"})
Actor "A" is being included as a value for actor2! But this makes sense when you think about it, because nowhere in your query did you tell neo4j that actor and actor2 need to be distinct entities.
Luckily it's easy to do:
START actor=node:node_auto_index(name='A')
MATCH actor<-[:INTERACTION_ACTOR]-interaction-[:INTERACTION_ACTOR]->actor2,
frame-[:FRAME_INTERACTION]->interaction
WHERE actor <> actor2 //like this!
RETURN frame, interaction