Two things come to mind...
Gem Dice: those that come with the numbers needing to be crayoned in. Even the one rolling the dice needs to squint to read them.....
And the player who is rolling his d20 'in the background' while the DM is dealing with another player, as if he's testing a d20 for how well it rolls. Suddenly, he 'just' rolled an 18 on his Spot check, which the DM did NOT call for.
Rather than make a copy of a characer sheet, I update my index cards, which have all the pertinent stats/info on them.
For tracking things like XP's, and items/trinkets, I use my journal, which I update after every game session. The journals make good reading many months into a game, too.