[{"_id":"xw5vk1s_PpJaal46di","users":["xw5vk1s",/**first element equivalent to from*/"PpJaal46di"/**equivalent to previously to*/],"like":true},{"_id":"xw5vk1s_abc","users":["xw5vk1s","abc"],"like":true},{"_id":"xw5vk1s_PpJaal46dj","users":["PpJaal46di","xw5vk1s"],"like":true},{"_id":"abc_xw5vk1s","users":["abc","xw5vk1s"],"like":true},{"_id":"ggg_xw5vk1s","users":["ggg","xw5vk1s"],"like":true},{"_id":"xw5vk1s_uuu","users":["xw5vk1s","uuu"],"like":true}]

db.collection.aggregate([{$match:{users:"xw5vk1s"}},{"$unwind":"$users"},{$sort:{users:1}},{$group:{_id:"$_id",users:{$push:"$users"},like:{$first:"$like"}}},{"$group":{"_id":"$users","count":{"$sum":1}}},{"$match":{count:{$gt:1}}}])