Aldi was split into two groups in 1960, along geographical lines (Nord and Süd, serving resp. the North and the South of West Germany). Aldi Nord operates as Trader Joe's in the U.S., while Aldi Süd operates as Aldi.
Aldi was formed by 2 brothers and then split after a disagreement about whether or not to stock alcohol. The reason I find it interesting is actually because Aldi isn't the first big brand formed by two German brothers to split into two (big, recognizable) brands. That honor would go to Adidas and Puma.