a) Ensure user is following the right process for dual pairing

b) Once the BT device is connected to Mobile Phone-A then make sure that BT device should again come into pairing mode before connecting to Mobile Phone-B or Laptop

c) Make sure both input device are not paired to any other BT device

d) BT device should not be connected to any previously connected device

Dual Pairing Process 

1. Connect the neckband with Mobile-A

2. Power off bluetooth of Mobile-A

3. Connect the neckband with Mobile-B

4. Now power ON the bluetooth of Mobile-A