Oh. If you have more than one piece, make an I-beam. This is the strongest shape for the weight. It is much stronger than doubling by connecting them to each other parallel to each other.
The notch isn't necessary. It adds strength and stiffness but a butt joint will be strong enough for your purpose.
The lower horizontal part probably isn't necessary either (so it might be a T-beam? I'm not sure that is a term)
Use screws, not nails. Sink the screws a little. Maybe dab a bit of wood filler in on top of the screw head and sand it even.
The notch isn't necessary. It adds strength and stiffness but a butt joint will be strong enough for your purpose.
The lower horizontal part probably isn't necessary either (so it might be a T-beam? I'm not sure that is a term)
Use screws, not nails. Sink the screws a little. Maybe dab a bit of wood filler in on top of the screw head and sand it even.