Pulling Double spawns Neutral Creeps, some Dota Allstars strategy - pulling double spawns means to aggravate a group of neutral creeps several seconds before a new bunch would usually spawn, then getting the creeps to follow you far enough that the game engine thinks there are no creeps anymore, and spawns a second group. With double spawns of neutral creeps, you can eran more money, read and enjoy.
The two small camps near the middle lane (3 Gnolls on the scourge side, 2 Trolls and a Kobold on the sentinel side) are the best camps for pulling double spawns because they will spawn the same creeps every time. Other spots have a chance to spawn Golems, which can't be damaged by Blade Fury or Centaurs, which are very hard to creep until level 5+, and even harder if you pulled double spawns.
You can see that there are now two groups of creeps, which means more gold per Blade Fury. Try to pull creeps while Blade Fury is cooling down so you don't waste time.
To pull the small camps near the middle, simply wait until 52 or 53 seconds after the minute, hit one of the creeps, and run away. The creeps should follow you, and new creeps should spawn provided you timed it right and ran in the right direction.
Creep respawning is based on an invisible rectangle around each camp. To make new creeps spawn, you have to get the original creeps to follow you out of the rectangle.
For the creeps on the sentinel side, you'll have to run directly to the right of the camp as soon as you aggravate them. Go up the hill and continue in that direction until the creeps turn around. On the scourge side, pull the creeps diagonally upwards, above the tower and the group of trees, but below the hill to the left. I know this might sound confusing, but it should be pretty clear if you watch the replays.