No. If you're talking about the Republican and Democrat candidate from a particular election, you're talking about two people. A choice between two people. Because each party puts forth only one candidate. Before that choice is made, they're not party candidates, they're nominees for candidate.

Hence the confusion. Granted, I'm unfamiliar with the poll itself. I'm just going off what you and the author said. The author of the article you commented on specifically mentioned one election year, 2020. Two candidates.

If that was an error on the author's part, you didn't address it in your comment, making your remarks nonsensical.