If there are certain characters (fandom or premades), you might be able to challenge the character but not the PB and they would take the best writer and the other is rejected.
If it's just a face, they take the best writer and that writer gets the PB and the other is asked to change but can still be accepted if their writing is up to par.
OR they just take the first one who applies. So if the challenger applies before you do, the PB goes to the challenger and you're rejected.