It's a funny scenario, but fortunately it's not a problem in the actual game. Having duplicate characters within the same vehicle has no negative effect on its behavior. There are some missions where the game requires you to not have any duplicate characters within the platoon (of up to 5 vehicles) in order to get certain rewards though.
*BOOM**GRAB**GRAB**CONFUSED*All crew members are Karina-chan!Fire~!All the Crew-members are Karina-chan!?
It's a Karina-chan festival ♪Alright~, here we go~!It's the enemy!*TREAD*Eh!Huh...?Who's the gunner?
I want to be the driver!I love being the driver too!I'll do the driving, so you others do the rest...*GRAB**TREAD*Which is which, this is...?Ah!It's aming this way...Move.
Move.It's a Karina-chan festival!!Fire!
Fire!
AiIiI
"ai" is Karina's catchphrase.*CONFUSED**CONFUSED**TREAD**BANG*