I tend to feel the hiccups in a very specific location and no where else on the baby's body.
With DD1 she stayed in one position (head down, legs to my right - I could always see her feet pushing out my right side) for many weeks and I would only feel her hiccups on my lower left pelvic area.
This one moves around more so I've felt her hiccups in three different specific spots, depending on how she's lying. One is the same place I felt with DD1, the second is just to the right of my belly button. And the their is just to the left of my belly button.
I have no idea what part of the body that is - I'm assuming close to her chest/diaphraghm.
I'm definitely only have one, not two kids.