Can I simply connect two AC/DC converters for increased current?
Connecting the outputs directly is not a good idea as there will always be a small voltage difference between the two. What happens then is that they will "fight" each other and whichever has the lower voltage will act as a current sink for the other. The crude solution is to put a diode in line with each of the outputs to prevent current flow back into the supplies. Unfortunately this introduces a voltage drop of approx 0.7V across the diode.

It's possible to run two supplies but you'll either want to divide the system such that each supply powers separate parts, or use a single larger supply.