A very cool approach would be to assign anagrammed names to your twins. In this respect, check out
www.behindthename.com/anagram.htmlThe names you mentioned yield the follwing anagrams:
Maille - Mallie
Raleene - Earleen
Moira - Mario - Omari - Maori
Felix - Flexi
Fiona - Afoni
Tyan - Naty
Tiernan - Trannie