Electricity price to go up 12 percent on August 1

"The electricity price in Serbia will still remain by far the lowest in Europe that is 50 percent cheaper than in Montenegro, twice as cheap as in Croatia"

Isn't that the same thing: 50% cheaper would mean it was twice as cheap because 50% cheaper means it is half the price. And if something is half the price then it is also twice as cheap because it would have to be doubled to be 100%.
So this statement suggests that both Montenegro and Croatia have the same electricity cost - one that is double of Serbia's.

"The electricity price in Serbia will still remain by far the lowest in Europe that is 50 percent cheaper than in Montenegro, twice as cheap as in Croatia"

Isn't that the same thing: 50% cheaper would mean it was twice as cheap because 50% cheaper means it is half the price. And if something is half the price then it is also twice as cheap because it would have to be doubled to be 100%.
So this statement suggests that both Montenegro and Croatia have the same electricity cost - one that is double of Serbia's.