Want to get "Single Flow Rate Sensor" value to be displayed on "2 Displays"

Hello everyone, I came to this forum after almost 8-10 years gap. I hope everyone doing well with their arduino’s. I have got a problem which doesn’t involve arduino but I know people here can solve this problem. I have a flow rate sensor(tachometer type) on a Nitrogen Pumping Unit which gives a flow rate that is displaying on a “SmartVue Model# SV06156” display screen, when I take the same 2 wires and connect separately to another display through “M8-6pin Sensor Cable” then it shows the same rate, but when I want to get the display on both screens using the same 2 wires coming from the sensor then the rate shown is different and irregular. I know there is a basic problem of current or voltage dissipation, can you just please let me know how to handle this or you have face any problem like this?