two-timer vs double-crosser

two-timer and double-crosser both are nouns.

Word	Noun	Adjective	Verb	Adverb
two-timer	Yes	No	No	No
double-crosser	Yes	No	No	No

As nouns, two-timer and double-crosser are synonyms defined as:

two-timer and double-crosser: a person who says one thing and does another

Other synonyms of two-timer include betrayer, double-dealer, traitor.

two-timer (noun)	double-crosser (noun)
a person who says one thing and does another	a person who says one thing and does another
someone who deceives a lover or spouse by carrying on a sexual relationship with somebody else