I am having a big problem remapping my keys

[open vessel]

I'm trying to remap my F key to D so I can use both D and F to click D but its like they both can't be used at the same time, I'm wondering if there's a fix for it that wont involve turning off rapid trigger here's an example of it happening
(https://www.youtube.com/watch?v=y1dx0huhWD8)