What is the ruling on my work for a company from which I received my salary in exchange for work done for another company, knowing that the time allotted for completing the work was exaggerated, and that this was encouraged by the officials to gain financially from the time difference? Do I have to return the excess money, given that I do not know the owners of the company?

An employee is entitled to their salary by their presence and submission of themselves to their management, whether or not they are assigned work. This is because a private employee is entitled to their wages by submitting themselves to their employer during working hours. So, as long as you have presented yourself for work and performed what was requested of you, the burden of the company's procrastination in completing tasks falls upon the company.