I’m not talking about the “so meaningful” prompt. I’m talking about “submit an essay on the topic of your choice” – where the topic just so happens to be a prompt from the other application.
Coalition prompt 5.
http://www.coalitionforcollegeaccess.org/essays.html
Common app prompt 7.
https://www.commonapp.org/whats-appening/application-updates/common-application-announces-2017-2018-essay-prompts
For example, is it OK to submit a Common App prompt 4 essay as a Coalition App prompt 5 response?