I still file for child support

How did the step father's name get on the birth certificate? We need more background here, also ANY question on law needs to include your general locale as laws vary by area.

I still file for child support

If he is named as the father on the birth certificate, he is the father, not the stepfather. So yes, if you aren't married and aren't living with him, and you are the custodial parent, you can file for an order requiring him to pay child support.

You may need to clarify here but it seems as though you are asking if you can petition for child support against the biological father. If you are, the answer is no. If the step-father signed the birth certificate, he is the legal father and he gets everything that goes with it. In this case, the biological dad can't be deprived of rights but still hold the bag for the responsibilities. The step-dad, however is still on the hook for child support unless the biological father were to challenge paternity in court. (In many cases, it isn't enough to prove that you aren't the father once legal paternity is established, you have to prove that someone else is. This of course depends on your locality, and we would be able to give you a much better answer if you would both clarity and add additional information)