importing records

I just imported over 6,000 records but no duplicate or multiple copies of a title seems to have made it into library thing. Any ideas? Thanks.

Oh, my. From an earlier post, it seems that I would have to add each duplicate copy as a separate record? Is that correct? That would mean getting a report from my old OPAC that lists all titles with more than one copy, checking Tiny Cat to see which copy made it into the catalog, and then manually adding all of these duplicates???