The Lighting Controller

Is there a difference between fader 2 and fader 3 when both are Dimmers?
Coz master dimmer 2 works as expected dmx000 @ -100% and dmx256 @ 0%
But master dimmer 3 is like this: dmx000 @ -100%, dmx128 @ 0% and dmx256 @ +100%
Tho I like how dimmer 3 works better than 2, I do think this is strange.
SW 8.2.6

"Master Fader" are proportional.
The result depends of the original value of the channel.

Yes, i get that, but they behave differently.
lamp 1 has dimmer on channel 1
lamp 2 has dimmer on channel 1
In a step file, i put dimmers for lamp 1 and 2 to DMX value 256
Now attach:
master fader 1 - speed
master fader 2 - dimmer - lamp 1 dimmer
master fader 3 - dimmer - lamp 2 dimmer

fader 2 will work from -100 to 0 % and 0 to 100% has no effect.
fader 3 will work from -100 to +100%

Is this correct proportion?

Please send your lightshow ; we will check that.