Why are you averaging the sensitivity of the 5A sensor (185) and the 30A sensor (66)?
The notion arrived from the features summary of the first page of data sheet. Now, your effort in the presentation of detailed information on the individual sensor has made me to understand that these sensors are indeed factory calibrated. Thank+ you so much to keep me educated.
from: what to use ACS712 or ACS758 for current mesurement - #7 by jremington - Sensors - Arduino Forum
All sensors can benefit from calibration.
The ACS712 can be purchased in three different versions, +/- 5, 20 and 30 Amperes full scale, each with different scale factors.
The factory calibration is supposed to be accurate to 1.5% of the full scale, but the user could improve that by careful calibration.