If you want to come accross as professional, please don't use both "screenply by" and "story by" on your cover if it's the same name both times. Save that for when different people perform those tasks.
Some films do show both, but on a script it makes you appeare desperate for credit, like your next note might say 'typed by,' or 'formatted by.'
It's enough to make a reader want to say Bye-bye.
