Dedup relationships with identical properties in Cypher

dedup_relationship.cql

MATCH (a) -[r]- (s)
// use two `WITH` clauses to build a sorted list
WITH r, a // a for group by
ORDER BY id(r)
WITH type(r) AS t, collect(r) AS coll, a
// identify duplications
WITH t, reduce(s = [], x IN coll|
	CASE any(y IN coll WHERE id(x) > id(y)
		                   AND y.KEY1 = x.KEY1
		                   AND y.KEY2 = x.KEY2)
	WHEN true THEN s + x
	ELSE s
	END
) AS del, a
FOREACH(x IN del| DELETE x)