That question came up on another thread. Verizon lists SXM as two different countries so it is possible to be charged $10 twice for the same day...but...a couple of posters stated that they were only charged once per day but used the product on both sides.

Personally i wouldn't risk it on SXM....anywhere else it works great (and only 2 bucks in Canada/Mexico)

Safer just to go for the monthly international plan