Mongodb error for duplicate indexes - node.js

Question

I am new to MongoDB/Mongoose and am in the process of dumping my localdb in order to create a DB for heroku. When I run mongorestore I get the following error(s):
2016-08-29T22:05:00.411-0500 building a list of collections to restore from /Users/micahsherman/tmp/mongodump/Loc8r dir
2016-08-29T22:05:00.518-0500 reading metadata for heroku_n1kxxxxxx.locations from /Users/micahsherman/tmp/mongodump/Loc8r/locations.metadata.json
2016-08-29T22:05:00.518-0500 reading metadata for heroku_n1kxxxxxx.test from /Users/micahsherman/tmp/mongodump/Loc8r/test.metadata.json
2016-08-29T22:05:00.519-0500 restoring heroku_n1kxxxxxx.test from /Users/micahsherman/tmp/mongodump/Loc8r/test.bson
2016-08-29T22:05:00.519-0500 restoring heroku_n1kxxxxxx.locations from /Users/micahsherman/tmp/mongodump/Loc8r/locations.bson
2016-08-29T22:05:00.520-0500 restoring indexes for collection heroku_n1kxxxxxx.test from metadata
2016-08-29T22:05:00.574-0500 finished restoring heroku_n1kxxxxxx.test (0 documents)
2016-08-29T22:05:00.799-0500 error: multiple errors in bulk operation:
- E11000 duplicate key error index: heroku_n1kxxxxxx.locations.$_id_ dup key: { : ObjectId('57c334af05803d85c7b9e780') }
- E11000 duplicate key error index: heroku_n1kxxxxxx.locations.$_id_ dup key: { : ObjectId('57c3819605803d85c7b9e783') }
2016-08-29T22:05:00.799-0500 restoring indexes for collection heroku_n1kxxxxxx.locations from metadata
2016-08-29T22:05:00.852-0500 finished restoring heroku_n1kxxxxxx.locations (2 documents)
2016-08-29T22:05:00.852-0500 done
These prevent a connection from Heroku.
I have gone into the console and printed the indexes, here are the results:
rs-ds017886:PRIMARY> db.system.indexes.find();
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "heroku_n1kxxxxxx.test" }
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "heroku_n1kxxxxxx.locations" }
{ "v" : 1, "key" : { "coords" : "2dsphere" }, "name" : "coords_2dsphere", "ns" : "heroku_n1kxxxxxx.locations", "background" : true, "2dsphereIndexVersion" : 2 }
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "heroku_n1kxxxxxx.objectlabs-system" }
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "heroku_n1kxxxxxx.objectlabs-system.admin.collections" }
rs-ds017886:PRIMARY>
I'm not quite sure how to go about debugging this. Thoughts??

Answer 1

Double check your locations.bson file to ensure you don't have duplicated documents ('57c334af05803d85c7b9e780' & '57c3819605803d85c7b9e783'). Looks like you're adding data before you create your indexes.
Here's an example of what I believe to be happening (hard to tell without seeing the data)
> db.people.insert({name: "Matt"})
WriteResult({ "nInserted" : 1 })
> db.people.insert({name: "Matt"})
WriteResult({ "nInserted" : 1 })
> db.people.createIndex({name: 1}, {unique: true})
{
"ok" : 0,
"errmsg" : "E11000 duplicate key error index: test.people.$name_1 dup key: { : \"Matt\" }",
"code" : 11000
}
the _id field already contains the unique constraint