Anything that is the masculine/feminine versions of a name eg:
Andrew and Andrea
Daniel and Daniella
Paul and Paula
Samuel and Samantha
Anything that rhymes eg:
Sam and Pam
Janine and Colleen
Ella and Bella
Eve and Steve
Any 'famous' pairs eg:
Mary-Kate and Ashley
Harry and Sally
Rosie and Jim
Bert and Ernie
Anything very 'matchy' eg:
Ruby and Sapphire
April and June
Daisy and Poppy
Cherry and Strawberry
Phoenix and Robin
Anything that is a variant of the same name eg:
Isabel and Isabella
Alfie and Alfred
Evie and Eve
Ava and Eva
And anything that creates a jarring difference in terms of crossing sterotpyped 'categories' of names eg:
Araminta and Tyler
Hugo and Keeley
Florence and Dexter
Frederick and Bailie-Rae