I like both names. Scar is a fitting name for a villain, but I think that Taka suited him too, when he was younger and - of course - didn't have his scar.
I think that Ahadi and Uru loved Taka just as much as they loved Mufasa, so I don't believe that they named him "garbage". Maybe they were thinking about the word "want" when they chose the name Taka. Taka must have been a bit difficult as a baby...
