The latest XM-L will produce around 1000 Lumens in optimal lab conditions, stick that in a light and you would be looking at around 700-800 max accounting for losses.
Those 2x XM-L lights would likely only be putting out 500-600 each max, so 1000-1200 max.
And its pretty unlikely that they will have the latest ones too, despite what it says.
To properly measure lumens, you need to use a sphere, the best most of us could do is to use a light meter and find the lux, but that only tell you how bright a light source is.
I have a 9x XM-L flashlight which is advertised as 11000 Lumens, tests showed it was about 5000 max when first switched on, going down to around 3500-4000 after the heat etc… kicked in.