Confusion about rangefinder and prx_type

I used two GY-US42 as rangefinder in I2C mode, and set the parameter following the link. I was trying to use the sensor to avoid object. in addition I set : AVOID_ENABLE=7, PRX_TYPE=4。in the proximity UI, it shows that the distance from two rangefinder are same all the time.
why the distances from different sensors increase and decrease simultaneously?
in the parameter list, there is only one PRX_TYPE, i did not find PRXx_TYPE? how to set the PRX_TYPE for every rangfinder?
any advice will be helpful ,thanks!

Maybe because they have the same i2c address?

i set different address for them