Rain amount

Using the latest version of WD 10.37b23, having rain but the amount that is showing up on my Acurite 1525 display and WD are not the same. Display shows .91 in rain but WD shows.64 in rain. What would cause the difference. This is a new 5 in 1 sensor and this is the first time it has rained. I have another 5 in 1 sensor and it is showing .90 on the display