MongoDB: Can a user insert same document multiple times in same collection ?

Question

suppose, I have an existing capped collection with the following syntax.

db.createCollection("mycappedCollection",{capped: true, size: 2, max:2})

Now, what i want is to modify the above collection and add the autoIndexId option.
like:

db.createCollection("mycappedCollection",{capped: true, autoIndexId: true, size: 2, max:2})

How can I modify the existing mycappedCollection?

Answer 1

Answer is "Yes".
A user can insert same document multiple times within a collection but system generates an unique "_id" for each document.