Also, a few systems have "00" mean 0 instead of 100, for example, Eclipse Phase,
http://www.google.com/url?sa=t&rct=...iW5uY9_qbW0hOoOX8OU_0DQ&bvm=bv.90790515,d.eXY. On the other hand, Dark Heresy, and other WH40K role playing games,
http://en.wikipedia.org/wiki/Warhammer_40,000_Roleplay, use the usual mechanic. Even games which usually use other dice types, for example D&D 3E, can ask for percentile rolls. Most folks handle such rolls on a 1-100 scale, with values of 1-20 being used to attempt a 20% roll. But you could also do that as 0-19 on a 0-99 scale. Many folks would find this confusing.
The value "00" + "0" turns into 100 because 0 is mapped to 100, not because the "0" is a 10, and not be cause "00" is a 100. For the first, you would get results like "40" + "0" generating 50, and "00" + "5" generating 105.
You could set up a dice system with values of 10 through 100 on one d10 and values of 1 through 10 on a second d10, but the range of values would be 11-110.
There is (a little) information here:
http://en.wikipedia.org/wiki/Dice_notation#Percentile_dice_.28d.25.29
Thx!
TomB