Not exactly. In altitude training you work harder for the same speed because of slightly less O2 available. Twice as hard, nope. I say go your normal distance at your normal intensity. I'm not sure such a short period of time spent at altitude will give you much of a noticeable boost once you return home to the lowlands. That said and it might just be my imagination I feel an effect when I travel over the mountain and down the hill to the Puget Sound region and ride. The elevation of my house is 1475 feet, most elevations of where I ride in the Seattle area is <300'. That difference is not supposed to be enough to matter perhaps it is the combination of the higher humidity plus lower altitude but I feel stronger and faster when I go west. Conversely when I ride over mountain passes >3000' I do not feel out of breath due to the elevation. Stopping to rest or take in the view my recovery is just as fast as when I am near home.