Not related to CitiBank, but I had a Chase card application go pending after filling out the particulars.

Somehow, when I logged back in it re-applied for the card - and both applications ended up approving. 2 unique card numbers and 2 unique cards on my online account access page.

I thought their system would catch it, but never did. Got the SUB for both, 120K Chase points for me!

I would try and meet the minimum spend on both if you could - best case you get 3 SUB, worst case you just get the RDM for the extra spend on card #2 and #3.
You can cancel extra cards and dump its credit limit into the other card when you want to downsize the wallet.