well single hose units inherently have much worse cooling efficiency.
It doesn't mean that yours can't cool the same but it will use more energy to do the same job. Simply, In a dual hose system the hot air is separate from the fresh air intake. In these cases the unit doesn't have to work any harder to cool that intake air. You can also use a thermal blanket on the exaust air tunnel so the heat exchange doesn't get back into the room you are trying to cool through the wall of the hose. And being in the same room as the hot air the units do not get to cycle normally as say a window air conditioner, they usually cycle very fast ie on and off repeatedly.
These single hose setups are just worse performers and cost more while doing the same job.