One of the first Otter creatures ever certainly took advantage of that keyword, and its companion condition is actually the condition for the Commander format in general (no two nonland cards in your deck share a name)
Before we talk about printing and sizes, there is another kind of proxy card to mention
Reign of Jafar - Ruby and Steel Best cards: Mulan, Charging Ahead
Cheap cantripsspells that replace themselves like Consider, Ponder, and Brainstormput cards in the graveyard for threats like Murktide Regent and Abhorrent Oculus that rely on a stocked graveyard for fuel
Each Dominaria United Commander deck comes with a Collector Booster Sample Pack, which contains two cards: 1 Rare or mythic rare that can be traditional foil, showcase, extended art, and/or a borderless planeswalker 1 Traditional foil showcase stained-glass uncommon Your Collector Booster Sample Pack might contain a special version of one of the cards in your Commander deck or a card perfect to add to another Commander deck