What can I claim if I provide a second immediate denture not long after the first?

This depends on the information on the initial FP17DC treatment plan. If the patient was advised that the first denture would be a 'temporary fitting' and that they'll require another, then this should be considered as one Course of Treatment (CoT). This is because 'Every component of the planned treatment' had not been provided and the CoT was not complete.

If however the patient was told that the treatment was an immediate denture and that further consideration would need to be given in a future CoT, it would be reasonable to consider these as separate courses of treatment.