If you say "DC Comics" you're really saying Detective Comics Comics. The same thing happens with "MLB baseball," "EDM music," and "HTTP" protocol. "PSA announcement." "LCD display." "POTS syndrome." "CAC card." "HIV virus."
When you open the door to other languages, it gets worse. Sahara means desert in Arabic, so the Sahara Desert is just the "desert desert." Chai tea is "tea tea" to people who know HIndi and English. Because "brea" is the Spanish word for tar, the La Brea Tar Pits are kind of like saying "the tar tar pits."
The phenomenon is called "RAS syndrome" (redundant acronym syndrome) and it was coined in a 2001 New Scientist column. You can read all about it on Wikipedia!
