I’ve tried submitting multiple times with shorter titles but I get the same error (as the second screenshot in the Imgur link) after I hit submit:
“Sorry, that story was previously submitted.”
<guess> You probably submitted the story once and see that it was killed (automatically). Then you probably deleted it and tried to resubmit it (with a shorter and longer title) (from your account and from other account).
Probably some of the automatic spam filters can detect resubmission of deleted stories, perhaps for a short time. This is probably to prevent spammers form resubmitting stories that are flagged/killed. You are not a spammer, but automatic filters sometimes make mistakes.</guess>
In any case, to get an official reply, send an email to the mods.