meaning of "然後三個三個分成小組" https://www.youtube.com/watch?v=n38D7DCDtbk

http://southworks.com/blog/2009/06/21/the-cookie-experiment/

So,when Liu Anting refers to "然後三個三個分成小組" does she mean something along the lines of "And then into three small groups of three?" 

曾經做過這樣的一個實驗 - 他們將一大群大學生招集起來之後 - 然後三個三個分成小組

They once performed this sort of experiment - [After] they formed a large group of university students - then they divided them into three groups of three".

Is my understanding of 分成 correct? Thanks!
X 个 X 个分成小组 means to divide something into groups of X. So 三个三个分成小组 means to divide these students into groups of 3. But the number of groups is not necessarily 3.
The expression &quot;X 个 X 个&quot; is something like giving an example of arrangement, or the manner to process a bunch of things, such as:

把这些苹果两个两个放在一起。    # two apples together
把这些苹果一个一个洗干净。    # wash the apples one by one