What exactly have you got? The “shop” emonPi has the Raspberry Pi inside the aluminium box, and the temperature sensor is normally external, connected using the RJ45 connector.
I would have thought so too, but I would not rule it out until it is proven good. Is yours a genuine Dallas/Maxim DS18B20, or could it be a “clone” - see Ds18b20 and emonTX3CM firmware - post 78 in particular.