masteries glitch

TLDR; other teamates masteries are showing up in my drop-down in ranked as my own.

summoner name: 4hed

In several ranked matches i would go to select my masteries, (and i like to have pre-made masteries because i CBA to create new ones every match) and i would see random names of masteries and random setups that i did not make.

i went out on a limb and ased the rest of my team "does anyone have a "azir mid" page as their third page?" and sure enough another teamates masteries were showing up as my own.