Blackstone Group and Partners Group Holding AG are the two remaining bidders vying for a controlling stake in Piramal Enterprises Ltd’s glass unit, people familiar with the matter said. The investment firms have progressed to the final round of bidding for India’s Piramal Glass, the people said, asking not to be identified as the information is private. Billionaire Ajay Piramal’s conglomerate is seeking a valuation of $1 billion for the unit from the sale, the people said. Piramal could name a winner as soon as October, one of the people said.