Ranti scored in the 29th and 70th minute while Trinidad and Tobago World Cupper Cornell Glenn had restored parity in the 59th minute.
The Kolkata giants have now got seven points from three games and are on third position in the league table.
The red and hold brigade got their first opportunity in the 23rd minute when Dudu Omagbemi freed Ranti whose powerful right-footer went wide.
But Ranti made amends within six minutes when he found the back of the net. Saumik Dey and Leo Bertos combined brilliantly on the wide left. The Kiwi international essayed a cross into the box and Ranti nodded home even as rival keeper Rehnesh TP had come out of his charge.
However Gaikwad made it up somehwat for that defensive lapse as his signature powerful long throw caught Rehnesh completely off-guard as Ranti scored his second hoal with a powerful nod to make it 2-1. The match was into its 70th minute.
Dudu should have added his name on the score-sheet in the 76th minute as he had only Aiborlang Khongjee to beat. However, the Nigerian's shot was weak and went straight to Rehnesh.
