You're arguing that because it's the same skill, you don't.
Correct, but allow me to elaborate on why.
Again, returning to the Rules As Written (RAW).
LBB2.81, p16:
One person may fill two crew positions, providing he or she has the skill to otherwise perform the work. However, because of the added burden, each position is filled with skill minus one, and the individual draws salary equal to 75%of each position; thus, to fill two positions, the character must have at least skill level-2 in each
So you have two positions to fill by one person.
When you have one person filling two positions, it's not a -1 skill per position ... or to put it another way, the skill on the character sheet doesn't get modified. Your character doesn't lose skill points.
Let's see if I can explain the different directions of thinking here, because the nuances of trajectory in the assumptions matter ... and I'm sorry for getting pedantic about this, but the mere fact we're arguing about this makes the pedantic obviousness necessary.
Think of it it terms of (basic) computer programming ... or even just simple algebra with variables.
You can either do (A-0) for a single position ... or (A-1) and (B-1) for a dual position.
The variables for A and B are database lookup values (go to character sheet, read in skill value). The arithmetic is not "editing" the values stored in the database (the character sheet), it's just a lookup to pull the value.
So if the value being pulled is ... 2 for A ... and 2 for B ... then the output of (A-1)=1 and the output of (B-1)=1.
With me so far?
So where are you getting the values for the variables A and B?
From the character sheet.
Does the formula "care" which skill is used for A and/or which skill is used for B?
NO.
All it cares about is that the skill being slotted in for A is at least Skill-2 and the skill being slotted in for B is at least Skill-2 ... so that after the (A-1) and (B-1) both A and B are still 1+ (with the one exception of Steward skill, because the minimum required is 0 not 1).
THAT'S IT.
Designers are then free to assign ANY SKILL to the A/B dual position assignment ... like Pilot/Navigator.
What is not prohibited per the Rule As Written is using the same skill for both A and B.
So a Gunner/Gunner with Gunnery-2 skill on the character sheet works like so.
There are two positions to fill ... Gunner1 (A) and Gunner2 (B).
A character with Gunnery-2 fills the Gunner1 (A) position using (2-1=1) Gunnery-1 ... while also filling the Gunner2 (B) position using (2-1=1) Gunnery-1.
each position is filled with skill minus one
each position ... (significant pause) ... is filled ... (significant pause again) .... with skill minus one
Gunner1 (A) position is filled with the relevant skill minus one ... Gunnery-2 (from the character sheet) minus one is Gunnery-1.
Gunner2 (B) position is filled with the relevant skill minus one ... Gunnery-2 (from the character sheet again) minus one is Gunnery-1.
A = 2-1 = 1 for position A
B = 2-1 = 1 for position B
The calculation of what skill amount fills position A
has no effect or relevance on the calculation of what skill amount fills position B.
(A-1) does not affect (B-1) in the formula.
If A and B are set to use the same skill, you do not wind up with (A-1) and (A-2) ... because position B is not skill minus two.
The B position is filled at skill minus one
independently of the A position skill requirement.
Not minus two ... minus ONE.
The Rule As Written is completely agnostic as to which skills can be slotted into the -1/-1 position formula in what combinations. It does not include ANY wording to the effect in the direction of an (A-1) and (A-2) interpretation like you're advocating for when A and B are set to draw data from the character sheet using the same skill for A and B.
The -1 to A has NO EFFECT on the -1 to B.
Why?
Because ...
each position is filled with skill minus one.
That means (A-1) and (B-1).
What you choose to fill A and B with as far as skill number from the character sheet is up to you, because A and B are variables.
The skill numbers on the character sheet
do not change just because of a crew assignment.
If I'm a Pilot/Navigator with Pilot-2 and Navigation-2 skills, while my character is filling my crew positions as a Pilot/Navigator I do not edit my character sheet to reduce my skills to Pilot-1 and Navigation-1 on my character sheet. I do not lose skill points on my character because my character is filling two positions. The skills on my character sheet remain unchanged. The only thing that changes is "how much" of my skills can be applied to each crew position ... -1 to the first position and -1 to the second position.
So my "throughput" for each position is effectively Pilot-1 for position A ... and Navigation-1 for position B, but the skills recorded on my character sheet remain unchanged.
If I'm a Gunner/Gunner with Gunnery-2 skill, while my character is filling my crew positions as a Gunner/Gunner I do not edit my character sheet to reduce my skill to Gunnery-1 on my character sheet. I do not lose skill points on my character because my character is filling two positions. The skill level on my character sheet remains unchanged. The only thing that changes is "how much" of my skill can be applied to each crew position ... -1 to the first position and -1 to the second position.
So my "throughput" for each position is effectively Gunnery-1 for position A ... and Gunnery-1 for position B, but the skill recorded on my character sheet remains unchanged.
"If none of this makes sense to you, it may already be too late."
- Shadoe Stevens,
Shadoevision