My son, who was accepted to Princeton, wrote two sentences for this essay. Like you, the information was also listed elsewhere in his application, so it was a bit redundant -- but, yes, you still are supposed to do it.
I was wondering about this short answer and the common app short answer. Are you just supposed to detail what you did or are you supposed to write it somewhat like your essays and include stories and how it affected you.
^^ It can be either. It depends on what you did for the summers, and how much you want to share (or write). I'm sure some students are accepted with longer, more descriptive essays, while others, like my son, are accepted with "short answers."