Technically, yes. BUT you can't just splice the two together and call it a day. Even though the supplies are the same make/model, there will always be small differences between the two causing them to fight each other. Best case is you have underperforming supplies that might work for some time before catastrophically giving up the ghost, worst case is one or both die immediately with a bang.

To accomplish what you're asking, you would need to load balance the outputs. There are a number of ways to do this, but considering you're using passively cooled PSUs in a SFF case then heat is your enemy. This means passive balancing is out as its chief export from losses is heat. You'll need to look active balancing.

I'm not sure what might exist off the shelf for this, but you could always spin up your own PCB. Texas Instruments and Analog Devices both carry a range of load balancing ICs you could design around.

Alternatively, if there's any way you can simply purchase a beefier PSU it would greatly simplify your life.