I have tried putting 2 pods one on top of the other in the machines common at Hiltons and they have too much resistance and the coffee squirts out the gap where the pod holder swings out to fill. But what does work is to use one pod with 1/2 cup water and another pod with another 1/2 cup of water. Another thing is that most European hotels have single serve instant Nescafe and I have been known to hoard the extra's and add them to the brewed in room coffee here in the US for extra strength.