No you don't have to tell each employer you have another job. Sure you can have more than 1 employer and W2 during the year and at the same time. Enter each W2 into the same tax return. After you enter the first one you can add another. Are you having a problem?
You only get one refund or tax due for all your income combined. The Refund Monitors won't be right until you have entered all your income. So don't look at it until you are done.
