[{identifier:"x",versions:[{name:"test_name",version:"x.x.x"},{name:"test_name",version:"x.x.x"},]},{identifier:"y",versions:[{name:"test_name2",version:"x.x.x"},{name:"test_name2",version:"x.x.x"},]}]

db.collection.update({"versions.name":{$exists:true}},[{$set:{versions:{$map:{input:"$versions",in:{$mergeObjects:["$$this",{title:"$$this.name"}]}}}}},{$unset:"versions.name"}])