Dallas Temperature Example: wrong values from sensors

[Heinz]

Hi, I used the DallasTemperatureSensor Example to monitor the heating of my house. All in all I soldered 8 sensors in a star-configuration and took the sketch without any modifications. Having a look at the plots in FHEM I noticed that the values are mixed up between the single sensors. So I modified the sketch and used the sensor address instead of the sensor index. Now the values seem to be the right ones.
It seems that getting the temperature by index sometimes returns the value of another sensor in the one-wire network. Any explanations?

On the left side of the picture there are the mixed vales... After the straight line I started the sensor with the modified sketch. The last vales seem to be reliable.