Those diodes are not on the same piece od silicon, but generally do come from the same die, and are relatively close to each other during manufacture, so are going to be reasonably well matched. However I would, as said above, derate them for parallel operation, and would rather regard parallel operation as a way to drop forward slope resistance and thus forward voltage drop under load, and run the pair at the same forward current as a single diode inside. Makes them easier to heatsink, as you have a lower heat dissipation from them. Drops the power dissipation from around 20W to around 12W using the 2 in parallel, making your thermal design easier. If you do need 60A choose a different dual diode rated for 60A per section instead, though you might be able to get away using 2 of the packages in parallel, making sure to match the trace lengths of the PCB to get the diodes to share current, using the PCB resistance as a rather poor but free ballast resistor.