On long haul flights that require additional crew members, airlines use various ways to meet the regulatory or contract requirements.
Many airlines add just additional First Officers (co-pilots). For some airlines this is not desirable because there is no Captain in command while the Captain takes his break.
Some airlines will add a second Captain on these long haul flights while a few have created a new position they call "Cruise Captain". This is usually a senior First Officer who has additional training and responsibility to satisfy the need to have a "Captain" on the flight deck for all phases of flight without actually paying for full Captain.
Some airlines have also created a junior position called "Cruise Relief Pilot" who is paid less than a regular First Officer and can only operate during the cruise portion of the flight.