It happens sometimes. There shouldn't be any problem, if you really haven't read the Dragonlance saga, your characters just CAN'T be the same. Raistlin is a very specific character and you can't create the same character if it is not exactly what you want to do. Also, the more important thing is the temper of the character, not how he/she looks like.
Actually I have read the Dragonlance saga but I never really imagine Raistlin to look this way You know, he was certainly not that fit plus his skin was... well... yellow And I don't even remember how Chrisann was supposed to look like.
However, I totally agree on that There are look-alike characters in almost every book/movie/gameby comparison, while you can never find to characters with the exact same personality
Still my comment was just a remark of surprise to this look-alikeness this illustration bears to my characters. (the fact that it resembles both of them actually... because it is pretty often to find a white haired man and a chinese/black haired woman in literature/art, it is just more rare to see them together)