Only show checkbox if there is more than one user involved

Only show checkbox if there is more than one user involved

diff --git a/assets/javascripts/discourse/components/bcc-checkbox.js.es6 b/assets/javascripts/discourse/components/bcc-checkbox.js.es6
index 43d89f5..32507a8 100644
--- a/assets/javascripts/discourse/components/bcc-checkbox.js.es6
+++ b/assets/javascripts/discourse/components/bcc-checkbox.js.es6
@@ -11,7 +11,7 @@ export default Component.extend({
       return (
         this.currentUser.staff &&
         this.creatingPrivateMessage &&
-        (this.targetUsernames || "").length > 0
+        (this.targetUsernames || "").length > 1
       );
     }
   )

GitHub sha: b45d10e2