Doesn't make a practical difference to me whether they're the same or not. The fact that the decimals go on infinitely is just a limitation of the decimal system anyway, so the discussion is vain to me. A third is a third and the fact decimals can't account for that doesn't make it some big mysterious number that goes on for infinity. It's still just a third. Three thirds together make a whole, so the number .999... is a human construct that doesn't exist in the practical world. .333... symbolises a third and .666 symbolises two thirds, so .333... + .666... equals 1, not .999...

Edit: Yeah, CMP said it first