Hi Pangit,
I have one set of magnetic tiles and use it with both, but I do have two kids using the program and have 2 student packs, but different levels. Two would be beneficial b/c you could easily keep track of what each child needs to review. For example, child 1 needs to review ch, sh, ea, while, with and child 2 has those down pat and needs to review ng, silent final e rules, chew, shoe. I’m sure you could figure out a way to make 1 set work for both, if need be, though. For me, it would be simpler to have 2 sets.
Blessings,
Christie