Then you also have polling firms that ask only one question, which party are you going to vote for in November and that is their total. Other polling firms ask you the same question but if you answer undecided, they will continue and ask which party are you leaning towards. Then they add up the two. Another polling firm may ask the first two questions and if you answer you are voting for a third party candidate, they may ask if he wasn't in the race, who would you then vote for.
All of this is listed inside the polls, but it take times to find.