To help you all out, the plants in common are Euriocaulon Cinereum, Alternanthera Reinekii Ocipus, and Ludwigia Atlantis.
However the "More than one person has one correct and its the same one but not the second plant" is kind of confusing. Do you mean to say that the second guesses are incorrect, or does the order of the guess not matter?
If so, we can assume that Euriocaulon Cinereum is plant #1, as it is shared by two people and is never in the second guess.
Ludwigia Atlantis is named three times, but appears only once as a first guess, I think we can rule this one out if my interpretation of Barthog's post is correct.
Alternanthera Reinekii Ocipus appears twice, but alternates as the first and second guess in both appearances, so we cannot make a definite guess on this one.
Again, this would only work if my interpretation of his post is correct, for all I know he could have meant to say something else.
I'm as confused as you are.