They`re Mirror 이미지 of themselves , but 당신 can say they`re twins . cause twin = 2 . and yeah . 팬 think of them as twins.
KEI stated in an interview that he specifically did not 디자인 them as twins, and was told the two are 더 많이 like mirror 이미지 of eachother and 디자인 them as such 의해 CFM. He said since he didnt 디자인 them at the same time (Rin came first), Len ended up looking a lot like Rin and was mistaken as her twin brother. He did not mean for them to be twins.
EDIT:
Len's voice is not altered in any way. Asami Shimoda was hired because she is able to create both male and female sounding voices. Len is Asami's raw voice without any editing :]
She sings as both Rin and Len in Rin Rin Signal (
link )