Need Help with a glitch in my pointshop

For example if there are 2 players on there both able to buy a T round this then bugs out and ends the round as soon as it starts.
Any help fixing this would be appreciated.
Also i would like to know how to add custom icons for items.

ITEM.Material = ‘VGUI/ttt/sprite_traitor.vmt’

that is the traitor icon. and if 2 people buy traitor they both will get it so the round should just end, maybe add a waiting system some how

thanks I already have that set as the icon however I would like it to be a custom one ya knw?