It is generally not a good idea to parallel the output of two power supplies. Both power supplies are unlikely to be at the same exact output voltage. As a result one will tend to try to supply all of the load whilst the other one will tend to idle along at low load. Depending upon the filtering characteristics used in the feedback networks on the two power supplies it is possible that oscillation could also happen.
Now all that said there are power supplies designed that are specifically designed to be able to be paralleled. These often have a special sense line that connects between all the power supply outputs that is used to support a balanced current sharing between the supplies. Designs of this type are more expensive and do add additional components to the circuit board. Current sharing supplies also have to add additional levels of fault detection to ensure safe operation/shutdown in the event that the common current sharing scheme fails or some component in a particular power supply fails.
It is not uncommon to see this type of parallel usage power supply used in server computers where power delivery is added in modular manner to the server as additional CPUs, memory and I/O boards are added to the server. Many of these power supplies contain internal microcontrollers that run sophisticated fault detection algorithms to make them safe in failure modes.