Why are two sources used when polls are taken?

Question

When polls are taken, why do they say "CNN and USA Today poll" or "CBS and New York Times poll"?

Why not just "CNN poll" or "USA Today poll"?

Answer 1

They aren't sources, they are sponsors.

The cost of polling is high, so the networks split it with a newspaper. That way, each gets an exclusive in the particular medium, at half the cost.

Answer 2

because they want to make sure that the results of the poll are accurate and not biaised

sereval sources have probably some little differences in the way they take the poll and the more diversity and the more people you get increases the accuracy of the poll