I kind of cheated on this one...
in reply to a message by Chrysanthemum
by doing 2 for each possible combination of twins.... but here they are:
2 girls: Anna Arwen and Lyra Liadan (or) Arya Anna and Leia Leonora
2 boys: Ruarc Riordan and Perrin Pascal (or) Ronan Rune and Paul Peregrine
1 boy 1 girl: Orion Odhran and Rowan Rhiannon (or) Gabriel Gawain and Morgan Minerva
2 girls: Anna Arwen and Lyra Liadan (or) Arya Anna and Leia Leonora
2 boys: Ruarc Riordan and Perrin Pascal (or) Ronan Rune and Paul Peregrine
1 boy 1 girl: Orion Odhran and Rowan Rhiannon (or) Gabriel Gawain and Morgan Minerva