A.C.
new cap, gown and tassel for each kid. a lot of times schools change colors, styles, etc for each year.
I actually still have my cap and gown, both tassels got lost somewhere along the line of military moves (or my kids tore them apart or something ... I really don't remember LOL) and I graduated in 1985.
Even if they were having the same style, color, etc (the schools here are the same year after year after year, not so when I graduated and not so in CA) I'd still get them their own set. It's THEIR graduation, not their brothers.