These brain twisters do come up every so often.
(Note: I2 does not stand for the number 12. I2 = molecular iodine, i.e., 2 atoms of capital i)
Here's the straight skinny from Trapper --
http://www.curezone.com/forums/fm.asp?i=1623991#i
one ml of Lugols 5% will have 100mg of KI and 50mg of I2 for a total Iodine content of 125mg
And here's the comparison from Bobby's Health Shop --
Their 7% Lugol's -- 1 ml has 50 mg KI and 25 mg I2 for a total iodine content of 63 mg. This is half the iodine content of 5% Lugol's, so I'd call it 2-1/2% Lugol's.
Their 15% Lugol's -- 1 ml has 120 mg KI and 60 mg I2 for a total iodine content of 151 mg. This looks to be 6% Lugol's.
It's been proposed before that their labelling practice includes the percent of I2 + KI, whereas the usual label for Lugol's reflects only the percent of I2. That's why their numbers look so large and impressive, while their solution is weaker than implied.
Honestly, I think all the different dilutions are "real stuff." It's just a matter of how many drops you need to get the dose you're aiming for.
They said the included dropper was metric, which according to their chart yields 3.15 mg iodine/iodide. That matches with thinking that the solution is 2-1/2%, since the usual 5% Lugol's drop is 6.25 mg iodine/iodide. Using their dropper, you'd have to double up what you've been doing. Using a different dropper for which you don't know the size drop it delivers, I wouldn't know what to do except guesstimate according to taste. Sometimes there's as much art as science in iodine therapy :)