Input DataFrame: rowsCount = 7, columnsCount = 5

name		age	city	weight	isHappy
firstName	lastName
Alice	Cooper	15	London	54	true
Bob	Dylan	45	Dubai	87	true
Charlie	Daniels	20	Moscow	null	false
Charlie	Chaplin	40	Milan	null	true
Bob	Marley	30	Tokyo	68	true
Alice	Wolf	20	null	55	false
Charlie	Byrd	30	Moscow	90	true

Step 1: Merge

merged	age	city	weight	isHappy
[Alice, Cooper]	15	London	54	true
[Bob, Dylan]	45	Dubai	87	true
[Charlie, Daniels]	20	Moscow	null	false
[Charlie, Chaplin]	40	Milan	null	true
[Bob, Marley]	30	Tokyo	68	true
[Alice, Wolf]	20	null	55	false
[Charlie, Byrd]	30	Moscow	90	true

Output DataFrame: rowsCount = 7, columnsCount = 5

fullName	age	city	weight	isHappy
Alice Cooper	15	London	54	true
Bob Dylan	45	Dubai	87	true
Charlie Daniels	20	Moscow	null	false
Charlie Chaplin	40	Milan	null	true
Bob Marley	30	Tokyo	68	true
Alice Wolf	20	null	55	false
Charlie Byrd	30	Moscow	90	true