Could duplicate mongo `_id` or not on 2 PCs?

I install my app on 2 PCs (A-PC and B-PC).
In the same collection Student, could mongo _id duplicate?
(Bc I need to consolidate data at Head office)

The _id field always has a unique constraint, so can never appear more than once in a collection.

Thanks for your reply.
But my one app installed two or more PC.
I am not clear, Could clerify?
(could duplicate or not in this case -> one collection)

Hmm. If you have 2 apps and 2 mongodbs, then yes - you can have the same _id from each app.

I have one app but install 2 difference PCs.
So it means that could have the same _id.
(I think that _id generate with PC, Board, CPU....)
Thanks again