My guess is that either paper or online, the applicant information must be entered into GCMS system so that an agent can work on it. The primary key could be your UCI number. If they detect two applications under same UCI, then it will generate new application number, and show both applications under the UCI#.
So when the agent logs into GCMS using their credentials, then it might show all UCI# numbers that are assigned to them. Under each UCI, it will show the application number/actual application. if anyone applies two times, then it will show two applications under same UCI# (Just a guess)
Based on that the agent could see both applications and might put both on hold and ask you why you submitted two applications (or) they might choose old one to continue. (or) they might ask you which one you want them to work on and ignore the other one.
These all are my guess work based on IT and take with a grain of salt.
Who knows they might pick up 2019 very soon. In any case, it makes sense to just wait. I know it is pain, but it is what it is. Good luck!