Kara no Kyoukai 7: Satsujin Kousatsu (Kou), Canaan Recommendations
Random simplistic story but with awesome animation!
The two series' protagonists have identical personalities, physical abilities, special ability and similar appearance.
There're some slight differences:
1/ Difference in eyes colors while activating their abilities. Shiki's eyes glows blue, while Canaan's turn red.
2/ Shiki uses katana and knives, while Canaan uses mostly gun
3/ They wear different styles of clothing. Shiki wears a combine of traditional and western while Canaan wear modern style only.