It's not that they sound the same, but rather the Japanese language doesn't have a distinct sound for "L" [in their alphabet] so it is replaced with an "R" sound. The Japanese used 'R.Parkers' to poke fun at their accent when pronouncing "Alpacas". This is why it wouldn't have worked if NoA stuck with the same name.
Same goes for Korea, they use ㄹ(rieul) to replace "L/R" and ㅍ(pieut) to replace "P/F" sounds depending on the consonant or vowel that follows after.
Languages are fun.