Originally Posted by
clr4t8koff
The tail number is simply the registration of an aircraft. It's the same thing as you having a liscense plate for your car. While I understand it was a different tail number, It doesn't mean anything if DL swaps one A320 for another A320. That doesn't alleviate them from paying IDB, whereas if they'd swapped in an A319 it would. For some reason you're not understanding that and bringing in tail numbers to the conversation. It's moot.
For some reason you seem to believe that swapping one aircraft for a different aircraft is not a change of aircraft.
The fact that the first part of the model number of the two aircraft is the same is completely irrelevant.