Thank you for the tip, Rony!
Unfortunately it doesn’t work. I tried it with only one sensor. I installed the library, I copied the sketch, I changed the #define DHT11PIN 2 to 0 (as I use that pin), it gives me no errors while verifying.
But once I run it on Arduino, it gives me “Read sensor: Time out error” which by the definition on the link it says “-2 : if a timeout occured, communication failed.”
Did you use the library yourself with the Temp&Humi Sensor module from Seeedstudio?
By the way, I tried to use the library from adafruit for the DHT11 and I had problems with that as well (you can check: http://www.ladyada.net/learn/sensors/dht.html for the tutorial from adafruit)