Nexus wrote:Will canceling this 2nd card hurt my credit score?
Immediate impact from closure is to utilization but with a $300 limit the impact may be negligible. Damage from the hard pull and hit to AAoA have already been done. You can try to see if US Bank will delete the account and hard pull since their staff indicated that they couldn't find your application but I have no idea what your odds are with that.
Next time don't rely on frontline staff to look into your application status.
Nexus wrote:What should I do with this 2nd card which is capped to 300 dollars?
That's your call to make. Is it useful to you?