Could "_id" of collection "A" duplicate or not, if I use it in my app at difference PC (more then one)?

For example I have Collection A, and the _id is auto generated by mongo.
But I install the app in difference PC: Head Office and Branch.
And then I have the backup/restore tool to consolidate data all of branch in the head office.
could _id of collection A duplicate or not (consolidate)?
Please help me.