Your deathadder is lazer.
No, no it isn't. You're confused because it says the sensor is 3G, this just means its a third generation sensor, both IR and laser happen to be on their 3G!
Taken from Razer on Deathadder:
1800dpi Razer Precision™ 3G
infrared sensor
Ergonomic right-handed design
1000Hz Ultrapolling™ / 1ms response
Five independently programmable Hyperesponse™ buttons
On-The-Fly Sensitivity™ adjustment........
The Lachesis
4000dpi Razer Precision 3G Laser™ sensor
The Razer Lachesis ™ reigns supreme with a true 4000dpi 3G
Laser™ sensor, which enables movement speeds of 5 times that of a standard 800dpi optical sensor. View the Razer 3G Laser white paper
32KB Razer Synapse™ onboard memory
With a 32KB onboard memory, you can store up to five unique gaming profiles.
Nine independently programmable Hyperesponse™ buttons
The Razer Lachesis™ allows programming of button functions while Razer’s Hyperesponse™ technology reduces latency for optimum gameplay.