In general, yes you can parallel two supplies. How well this works depends on how well they end up sharing the load current. This depends largely on a good match in the output voltage of the supplies. If one is at 12.0 V and the other at 12.2 V, then the higher one will supply most of the current and the lower one will be idle.
You need to wire it up properly and neither of your diagrams is right. Do not run a wire from one supply to the other then to the load (terminal block). That will absolutely prevent current sharing. Instead, use two identical sets of wires, one from each supply to the load (terminal block). The wire has some resistance, and this forms a ballast resistor to help to ensure sharing of the load current. For this reason, you should also not use really thick, low resistance wire. Instead use a smaller gauge, but ensure that it can still safely pass the current and doesn't cause excessive voltage drop.