What does this mean? As you know, with regular dice there is a fixed probability of rolling a given sum (you can roll between 2 and 12) when both dice are thrown. The same holds true for Sicherman dice; you can roll a sum between 2 and 12 and the odds of a particular sum occuring is the same as for a regular pair of dice.
For example, regular dice have a 1/9 chance of rolling a sum of 5. With Sicherman dice, there is also a 1/9 chance of rolling a sum of 5.