The customer care staff do know about this feature. They call it 'Parallel Ringing'. Both the agents with whom I spoke told me that the feature was launched for a few days for testing and it has been disabled now. But when I tell them that if the feature is disabled then the parallel ringing should stop, they have no answer. They tell things like 'Clear cache', 'Reinstall app', etc. for the sake of saying something. One lady even told me to check my mobile with the manufacturer. She said the mobile might be faulty. I just hung up the call after hearing this😂