Although I see some similarities between the two columns of Marianne signatures on this page, I also see many differences. Indeed, I am a bit surprised to notice that the a's of all the Mariannes in the left column are never connected to the letter in front of it. (The bottom signature shows a connection at the second "a" but that's because the "a" crowds the character in front of it, not because it is cursively connected to it.) So all the Marianne's in the left column are actually written as three separate groupings of characters:
M ari anne
On the other hand, all the letters of the Mariannes in the right column are cursively connected to each other. The top signature appears a bit faded but it looks like the first "a" is still cursively connected to the "M" in front of it. So, unlike the first column, the Mariannes in the right column were written as one continuous group of letters.
Given there are other differences between the cloumns as well, I have to agree with you that the two columns were probably made by at least two different people.