Ok issue was indeed unique index being not there/corrupted. I a guilty of adding the unique index later on in the game and probably had some dups already which prevented Mongo from creating indexes.
I removed the duplicates and then in the mongo shell did this:
db.orders({name: 1}, {unique: true, dropDubs: true});
I would think the above would remove dups but it would just die because of the dups. I am sure there is a shell way to do this but I just did it with some js code then ran the above to recreate the index which can be verified with:
db.orders.getIndexes()