Errors attempting to insert duplicate values

I have a table with a unique index. When I go to insert a new value into
the table my code does not know if the record is already there. To me there
are two choices:

1) Do a select for the record and insert only if not found.

2) Do a blind insert and relay on the unique index to fail the insert if
there is a duplicate.

I have chosen to do #2 and it has worked well for a long time. It seems
better to keep the number of database interactions to a minimum. The only
problem is everytime a duplicate insertion is attempted an error is printed
in the log file.

The anal-retentive part of my personality is bugged by this. What do other
people think? Is the technique legitimate and should the database be
reporting errors for legitimate operations?