There are items which say that you can spend surge abilities twice.
Red Scorpion's Flurry of Blades allows you to use it three times per round.
Now I guess rules as written means that you can't use those items with flurry of blades, you can already use it twice so it doesn't give you any new powers.
We played it as "use it one more time". Although in theory you could also say it would allow you to use it six times, if you had enough surge since that is "two uses" of her surge power.
I would agree with your latter conclusion if the card said that you could activate it "an additional time", but since both of the items set a number (2 and 3), I do not believe that they interact in any beneficial way.
I also don't believe anyone has asked this question before, so there has been no official answer... Although, official answers from FFG are fairly rare as it is.