Hello there, sabinepachamama,
If you're referring to importing your company file again, it will override the previous one. You can only import one company file per QuickBooks Online account.
Furthermore, QBO allows you to import multiple invoices. What invoice type were you referring to? You can check out this article to learn about the process: Import multiple invoices at once.
If you're referring to something else, please leave a reply so we can assist you further.