import ignoring duplicates

I am using psql's \copy command to add records to a database from a
file. The file has over 100,000 lines. Occasionally, there is a
duplicate, and the import ceases and an internal rollback is performed.
In other words, no data is imported even if the first error occurs near
the end of the file.

I am looking for an option/switch to tell psql (or the \copy command) to
skip over any duplicate key constraint viloations and continue to load
any data that doesn't violate a duplicate key constraint. Is there such
an option?

Mark