Thanks guys.
The measurement is not reliable when it comes to signal strength. It was taken wit both senders at the end of a corridor i the same place. The dB of both senders is similar.
However, there seems to be a frequency offset. Is this acceptable?
Update:
Different receivers act differently. One receiver passed the range check with antenna collapsed. The other failed.
If you think the frequency offset is within specs I will test fly using the good receiver.