Welcome Aboard!
Looks like you have a TT, and not of 5ver. Those hitches are only designed for a cargo rack. 300 pounds is all it can handle.
Most states do not allow double towing if the first trailer is not a 5ver. I would strongly recommend verifying your state laws, and any state laws in route to where you are travelling. It is illegal here in Minnesota, but I still have seen rigs on the interstate with illegally towing setups. So just because you saw someone doing it does not mean it is legal, so please do verify.
Edit:
This map is old, so I do not know if it is still valid or not. But it looks like most of the east coast does not permit double towing.