Hi, @Lyn1311
I'm sorry for the late reply.
First of all, Psychic Marina NPC that changes the IVs and nature in exchange of reroll tickets save the last 3 IVs of your legendary.
Note that the skipped IVs when a reroll ticket is consumed also gets saved into the system, so you have to be-careful when trying to save your IVs with the system.
Moreover, when you change your IVs of your legendary, the previous IVs will be saved into the system.
I would like to inform you that this system was created to help players who accidentally changed or skipped the desired IVs to keep.
So, it could be a little difficult to save multiple IV sets of a legendary.
Since, the previous IVs will be saved into the system as the last 3 IVs when exchanged, it seems like you are able to save around 2 IV sets for each legendary.
I hope this helped you answer your curiosity.
Have a nice day.
Kind regards, HappyMango.