Maybe soneone along the way is getting things mixed up - there's an "Indian Ocean Pass" operated by Air Austral, Air Seychelles and Air Mauritius that gives discounts on itineraries of 3 or more inter-island flights between various Indian Ocean island groups (including Madagascar, Reunion and the Comoros) if you fly into the region on one of the 3 participating carriers. Not much use to OW flyers!

Info at https://www.air-austral.com/indian-ocean-pass.html