If the Person doesn't get a confirmed ticket on the A/c, then i don't think it will happen again, since the A/c tatkal booking would close at 11.00Am and therafter the Non A/c booking would start, This entire process will culminate by 12.00 for both A/c and Non A/c, As per the reports. How this far this process would work in actuality is entirely a different question, which even the IRCTC would know, i'm assuming