When you import an OSP Bid Package file and the Bid already exists in the current (Active) database, the Bid is overwritten (you will be prompted to allow, of course). If you overwrite a Bid, any changes made to the existing Bid are irrevocably lost.
If in doubt, do not click "Yes" to overwrite the Bid! Create a new database and then import the OSP file into that database. You can then copy and paste the Bid into the first database to create a copy of it.
If you are using DPC you must always overwrite the existing bid to maintain the integrity of your DPC data.