Is in that already the case?
I haven't played single T-34-85 call in commander like in ages but I vaguely remember its price being 140 ish fuel for a single one.
The reason double call in is cheaper is because you get a discount when you buy two. This applies to everything, even shreks. At least that's what Relic have said some time ago.
The call-ins don't exist any longer for 34/85, they are T4 unit now and the price was lowered to not make it too steep or arrive too late compared to old call-in.