Illogical English #20

The expression “back-to-back” is used to mean “consecutive”. For example, “Mo Farah achieved back-to-back Olympic gold medals in the 2012 and 2016 Olympic Games.”
However, it’s illogical. If two things are consecutive, then surely they would be back-to-front, not back-to-back.
There is a problem here, though, because “back-to-front” already has another meaning – for example, when someone puts a T-shirt on with the front side against their back.