As described by TK67 in Fhem forum, get_device_reading returns inconsistent information, if a device has two readings, with one reading-name being a longer version of another reading, e.g. if readings myReading and myReading2 exist, then asking for myReading2 would wrongly also return results for myReading.
As described by TK67 in Fhem forum,
get_device_readingreturns inconsistent information, if a device has two readings, with one reading-name being a longer version of another reading, e.g. if readingsmyReadingandmyReading2exist, then asking formyReading2would wrongly also return results formyReading.