The decision is not a result of an attempt at a back-to-back data gathering exercise, but is simply down to the preferences of the individual drivers.
The team took a different direction with the upgrade package, first seen at the United States GP last month, and has since earned some solid midfield grid positions.
However, the cars are still proving hard in their tyres over a race stint, leaving the helpless drivers to drop down the order.
“The main drive behind this was Nico feels that for him the old spec suits him better, and Kevin is the opposite,” said team boss Guenther Steiner of the decision to run both versions.
“We’ve opted to give them what they want, we have two races to go and nothing to lose, so we’ve tried to do what we can.
“We could discuss gathering data, but we’ve got enough data, it’s a decision based on what each driver likes more than anything else. It puts them in a comfortable position so that they’re as happy as they can be with the car they get.”
Regarding the specific challenges of the night event, he added: “The low temperatures are a challenge, as everyone knows you need to keep the tyres higher than the minimum temperature, which is higher than five degrees, so we always need to keep them a bit warmer, but it depends also a lot on the asphalt.
“It’s a combination of temperature and roughness of asphalt, but I don’t think degradation can get much worse for us than in Brazil. On Thursday, during practice, we’ll get to know the surface, the track, the temperature and then we’ll know more.”
Steiner indicated that the main issue in races is tyre surface overheating, caused by excessive sliding, and he stressed that it has to be solved for 2024.
"We're learning what doesn't work, but I think we need to fix it,” he told Autosport after the Brazilian GP. “We know what we need on the aero. But we still need to make it, obviously.
“We are going in the right direction I hope in the wind tunnel. And for next year, we will cure this, we'll learn about the cooling of the rims, and all that stuff.
“At the moment, we don't have a big issue any more with the carcass temperature, it's just the sliding, the surface overheating now.
“You learn bit-by-bit, but we cannot keep on learning, we need to give some results, to be honest. At least we’re doing something, because the other car just didn't work."
Steiner made it clear that the tyre issue was still very evident at Interlagos, the team’s third race since the update package was introduced.
After repairs to damage sustained in the startline accident were completed during the red flag period Nico Hulkenberg eventually finished 12th, beating only the cars that were a lap down from the restart.
"Nico struggled so much,” said Steiner. “It's all management. It's not racing, it's management. It's a pattern of the whole year. It's not just the rears, it's all the tyres, we just have big deg, we just cannot keep them alive.
“But look at the Mercedes. What is it that some cars are doing it good, and some are bad? The Aston was good, but the Ferrari was degging as well.”
Hulkenberg confirmed that his Interlagos race was all about tyres.
"We were just behind the whole time consistently, but far away, really having to manage the tyres a lot,” said the German.
“If we push, we really damage the tyres. But for me it's a function of this old rough tarmac which really seemed to hurt us.”
