When a recommender writes you a letter of recommendation, the letter will be sent to all colleges that you’re asking them to write for. This is why counselors/recommendors should not tailor a letter to a specific campus:
Here is a note from the common app recommender guide:
"Important note: The Common App for recommenders is a one-and-done process. That means that once you submit a form, it’s sent to all the colleges you’re assigned to. That’s why it’s important not to customize your forms for a specific institution. "
I hope this helps!