Nick Heidfeld's Renault will be fitted with an experimental Red Bull-style rearward facing exhaust on Friday at the Nurburgring.
According to Auto Motor und Sport, the sister R31 driven by Vitaly Petrov will still be featuring the team's innovative front-exiting exhausts, which have been used by the Renault drivers throughout 2011 so far.
The report said the team's split approach is for two reasons.
"First, Renault can make comparisons with the old layout, and secondly because there are still problems with the weight (of the new solution)," said Auto Motor und Sport.
The report said that if the new system was fitted to Petrov's car, the sizeable Russian would tip the scales above the minimum 640kg car-plus-driver weight.
"We have had some problems over the last couple of races," said German Heidfeld, who is 15 kilograms lighter than Petrov, at the Nurburgring.
"We are trying to beat Mercedes. They just overtook us at the last race and that's what we are targeting."