Steps for reproduce: Start cluster with 2 replicasets with 3 nodes in each; Run commands: > use test > db.foo.insert({_id: 1, a: 1}) > sh.enableSharding( "test" ) > sh.shardCollection( "test.foo" , { a: 1 }) > sh.splitAt( "test.foo" , { a: 10 } ) Wait few seconds for balancing `test.foo` > sh.status()                         { "a" : { "$minKey" : 1 } } -->> { "a" : 10 } on : rs1 Timestamp(2, 0)                         { "a" : 10 } -->> { "a" : { "$maxKey" : 1 } } on : rs0 Timestamp(2, 1) Run commands: > db.foo.find() { "_id" : 1, "a" : 1 } > db.getMongo().setReadPref( 'secondary' ) > db.foo.find() { "_id" : 1, "a" : 1 } { "_id" : 1, "a" : 1 }   Expected result: second db.foo.find() returns exactly one record. Actual result: second db.foo.find() return two records (one orphaned records from `rs0` shard and actual record from `rs1` shard).