There are several solutions. One of the most popular naming methods is to choose names with the same initial (Megan and Mark), or use the same last letter or sound of the name (Angela and Nicola). You could name your babies after grandparents, perhaps after both of their grandmothers. More unusual methods could be using themes to match the names, such as geographical names (Paris and Athens) or biblical names (Isaac and Sarah) or names from Greek and Roman mythology (Helen and Athena). You could give names that have the same meaning but from different languages, such as Columba and Jemina, both mean dove but one is Latin and one is Hebrew. You could also give them names according to birth order, (a handy option if you have triplets!) such as Alison, Brian and Cate. If you babies are identical should they have names that rhyme?
Most parents are comfortable with picking names that may not be associated but sound good together. It is probably most important that the names you chose are a good fit with your family name.
Here are some fun ideas:
Aidan and Nadia – Aidan is Nadia in reverse
Amy and May – the names are anagrams of each other
Cara and Mia – Mia means ‘my’ in Italian, Cara means ‘beloved’
Erica and Heather – Erica means ‘heather’ in Latin
Melanie and Phoebe – are Greek, but Melanie means ‘dark’ and Phoebe means ‘light’
Rose and Lily – form a botanical theme
Wattenberg, Laura. The Baby Name Wizard: A Magical Method For Finding The Perfect Name For Your Baby.