The concept of getting command from only one superior is called Unity of Command.
Employees cannot follow orders from more than one superior. Hence this principle suggests that employee should get order from only one superior for any job or activity.
As per this principle, an employee should be responsible to only one superior or department for a particular job.
This principle prevents any confusion that may arise amongst employees with respect to whose order to follow. If order comes from more than one superior then it creates confusion amongst employees and hampers industrial discipline.