I think there is a bug, python's documentation does not make this as clear as it should.
The difference between your two parameters to jumpahead is 1, this means you are only guaranteed to get 1 unique value (which is what happens). if you want more values, you need larger parameters.
EDIT: Further Explanation
Originally, as the name suggests, jumpahead merely jumped ahead in the sequence. Its clear to see in that case where jumping 1 or 2 places ahead in the sequence would not produce independent results. As it turns out, jumping ahead in most random number generators is inefficient. For that reason, python only approximates jumping ahead. Because its only approximate, python can implement a more effecient algorithm. However, the method is "pretending" to jump ahead, passing two similiar integers will not result in a very different sequence.
To get different sequences you need the integers passed in to be far apart. In particular, if you want to read a million random integers, you need to seperate your jumpaheads by a million.
As a final note, if you have two random number generators, you only need to jumpahead on one of them. You can (and should) leave the other in its original state.