Just because it has the ports doesn't mean it has the internals to support them. I would check that before doing anything not to spec... it's a power supply.
If they bothered to mount extra connector they didn't bother to remove rest of the parts, I'd imagine the connector is connected to same power rail anyway.
It's still probably at wattage as advertised, but I wouldn't be surprised if some models that differ by "only" 100W had only difference being current limit resistor set on the different value.
> If they bothered to mount extra connector they didn't bother to remove rest of the parts
This is not true, as a rule, even if it is true here. Sibling comments point out that the void left by the missing connector would be tricky to fill.
There are a variety of other reasons that it might not be worth their time to change or omit the $.08 connector, but it would be worth their time to remove e.g. the expensive $3 voltage regulator IC.
But to your point, the same logic may be applied to the sticker-vs-PCB tradeoff, and it may turn out that they are identical. Someone disassembling them and comparing the circuits would be able to determine between the two cases.