Some of the 'Mollies' on the dreaded Wikipedia:
Mollie Arline Kirkland Bailey (c. 1844–1918), American circus musician, singer, war-time nurse and alleged Confederate spy
Mollie Hardwick (1916–2003), English author
Mollie Hunter (1922–2012), Scottish writer
Mollie McConnell (1865–1920), American theater and silent film actress
Mollie Orshansky (1915–2006), American economist and statistician
Mollie Phillips (1907–1994), British figure skater
Mollie Skinner (1876–1955), Australian Quaker, nurse and writer
Mollie Sneden (1709–1810), ferry operator before and after the American Revolution
Mollie Steimer (1897–1980), Russian-American anarchist, trade unionist, anti-war activist and free-speech campaigner
Mollie Sugden (1922–2009), British actress
So no, not modern, and no, not made up. Very old in fact, but possibly more New World than British spelling? - lots of Americans here.