Magento 2.1 admin logged in issue in session

To disable this feature go to

Stores > Configuration > Advance > Admin > Security

and

change value of Admin Account Sharing to Yes.

Follow below attached images screenshot to enable admin account sharing options from Magento admin panel. Either way you can go to Magento 2 admin>

Store>> Settings>> Configuration >> Advanced >> Admin >> Security and change ADMIN ACCOUNT SHARING Options to YES