Can I ask why you need 2 different days to do a character greeting? Maybe this is one reason other people can't get even one meet and greet? Maybe WDW should do what they do with ADRs and not allow someone to book more than one FP+ for the same attraction. Just seems a bit selfish to me and I can't understand why someone would need to meet them twice.
Yes, you may ask why, but it sounds like my answer may not matter since you find my choice is selfish already...
I believe the FP+ system allows everyone with a ticket the same
opportunity to book 3 FP+s/person/day prior to their trip. They have rules such as tiering at some parks to distribute these. However, getting a FP for the same ride, meet and greet or show/parade, is certainly allowed by Disney, if it is done on different days. I did not get an "extra" FP+ by booking A/E for two different days. I used 2 of my FP+ opportunities for this meet and greet, and had to give up doing 2 other FP+ experiences in return. So I don't believe it is universally unfair to repeat an experience via FP+. It might seem unfair to someone who wanted to do A/E, but it actually helps someone who, for example, wants a FP+ for Wishes those two nights. Wishes is not a priority for me, so I did not choose to use my FP+ for Wishes, thereby leaving it open for others to choose. Everyone gets the same number of FP+ opportunities, and I believe they can use them as they wish to make the best trip for their family. I am not gaming the system. I stayed up until Midnight to book it on the first night, I researched these great threads so I would know how to do it efficiently. Others have the same opportunity.
In addition, my taking a FP+ for any ride, M&G, show, etc does not
prevent anyone else from that experience. Everyone has the opportunity to do these rides and events
standby, if they are unable to get a FP+. That's what we will be doing (standby) on other rides and shows on our MK days, as that is the trade off for using our FP+ slots for A/E.
Why would we want to meet them twice? Because I have two daughters who absolutely love Frozen. Why would someone want to ride a particular ride twice? Same reason. Have priority seating for a favorite show twice? Same reason. Everyone has to choose what works for them. We can only visit once per year or less, so we prioritize the most important things to our family.
And I do believe that you can absolutely book the same ADR during a trip twice.
Thanks to all of those who posted as to their own reasons for booking the same ride/event/show twice in one trip!