Its been a few years, but if my memory serves me correctly, there were 3 or 4 of these hybrid machines. I think they came about because they were the last of the A model airframes, build with Arriels, (not converted), but Sikorsky were no longer producing the 045 Gearboxes, so they were fitted with the 046 B and C gearboxes. Sikorsky only rated the engines at the 1S level, as the A airframe would not take the full 1500 shaft horse power of two 1S1s. In conjunction with Sikorsky we realised that this aircraft would benefit from the full 1S1 single engine power, as the airframe was lighter than the B or C, this would give it an enhanced single engine performance. We had to contract an instrument specialist to modify the Torque Indicators to reduce the twin rating. I am a bit rusty now, but I think the limit was set at 80%.
Helitalia had another of these machines, although not in VIP trim, we told them what we had done to improve the performance, but I don't know if they acted on the information.