I used both item1 and fluid1 item in my filter blueprint, in order to use either one of them. But removing the not-used one doesn't apply in station name (still have fluid1 signal for exemple). It does work for constant combinator so I think it's a bug.
Not sure if I'm clear

Not so much a bug as an unimplemented feature. I actually attempted to implement this feature in v0.1.3.

Unfortunately, there are multiple ways to clear a configured setting and each one has to be handled depending on the type of setting. My code isn't flexible enough to implement this feature without updating the code for every configurable setting. So, instead of pushing a huge change and breaking things, I'm going to target this for v0.1.4

It's on my Todo list 🙂

Okay thanks. You say there is multiple way, is it on the user side? Is there a currently working method? (to avoid you needing to update)

Sorry, yes, using the factory mod API. Some signals require an empty object {} (SignalID) while others need a nil value or {type="item"} object