rserv replication error

I'm doing a little testing of rserv here.  Does anyone recognize the
issue with this error?

$ InitRservTest
$ psql -d master -c "update test set k = k + 1000"
UPDATE 100
$ psql -d master -c "update test set k = k - 1000"
UPDATE 100
$ psql -d master -c "update test set k = k + 1000"
ERROR:  _rserv_log_: duplicate tuples

Thanks,
Ed