If you have the nerve.
Do a backup and make sure it is valid or will restore.
You must create a header file from admin, in Import. All fields.
Export the entire database in an excel file. Sort by the suspect dupes, address, constituent code, etc. Do the editing. and then import back to Blackbaud. If you don't know how to do an export, I suggest you talk to support and they can walk you through it. I have 30 dupes out of 57,000 records, and they are dupes because of the first name is like "Memphis".
You would need to run your dupe report and make sure they are actually dupes before you do a merge also.
There is a lot more detail in doing this. I'm just giving you a summary idea on how to get rid of your dupes.
Get out your manual and go to import. It will give you the field names for your import file. When you do the import file you must create an import id, or export the one that resides in the database. This sounds like a lot of time to do this but it will be much shorter than 90 hrs.
Good Luck.