I was given an old 2' under-cabinet light fixture that used to be a magnetically ballasted F20T12 fixture but the idiots that manage the apartment complex I live in converted them to LED tubes (about a year ago) and they are now tossing all of them out and replacing with decorative LED fixtures. (new ballast and LED tube still inside old ballast is gone which is not a surprise:( )

Anyway the ballast is an Advance IOPA-2P32-LW-N and has the standard instant start wiring diagram (One wire to each lamp holder that are non-shunted sockets with a jumper so that is fine).

The ballast is a two lamp model but can be wired for one lamp operation just use one blue wire and insulate the unused one. I gave the LED tube to a friend and I went a bought a Philips F17T8 so my question is since this is a low ballast factor ballast what will happen if I use both blue wires to the same lamp? I don't care if I fry the ballast but I don't want an exploding glass tube I just want it a little brighter. Thanks  

first power factor dont have nothing to do with lamp brightness.  it just means current not in phase with voltage that all it means. 

u can stick that other wire in your  lamp holder
to  increase your lamp current.  I would change lamp to F20T12 since you double your output current.  As put your ballast in lamp over drive mode.  it will drive the F2OT12 nice and bright.

I did not mention "Power Factor" I said "Ballast Factor" I just don't want a lamp explosion. I just wanted to make the F17T8 brighter but I will convert it back to a F20T12 I already have a ballast for it, just have to buy another lamp. The original ballast is "MIA" but it was a trigger start one as one of the sockets is a current interrupting lamp-holder and I don't see a starter or even a place to put one

what will happen if I use both blue wires to the same lamp? I don't care if I fry the ballast but I don't want an exploding glass tube I just want it a little brighter. Thanks

That's known as wiring it for 2x overdrive.
You'll increase the lamp brightness somewhere between 1.5x and 1.75x with a T8.
I've done it multiple times with F32T8's. You can even do a higher overdrive & its still not gonna explode. Be aware that the end of the lamp might crack at EOL if you let it completely finish off.

Oh and that crap circuit-interrupting lamp-holder...either junk it, or connect both wires on the interrupting side together to disable the problems it may cause.