Mistress of Madderlea / The Wolfe's Mate (Regency Lords & Ladies #11)

Mistress of Madderlea by Mary Nichols
Miss Sophie Roswell wanted to marry. But as she was an heiress, surely her money would attract the wrong kind of man? Her ingenious solution - to switch places with her cousin Charlotte for the Season!

When she met Richard, Viscount Braybrooke, she knew she'd made a terrible mistake. Although he was looking for a wife, he had to fulfill his duty as heir to a dukedom. And Sophie was now apparently ineligible...

The Wolfe's Mate by Paula Marshall
Unbeknownst to Miss Susanna Beverly, her stepfather had cheated her out of her rightful inheritance. Thus she was forced to become the companion of Miss Amelia Western, who was betrothed to Viscount Darlington. Who would have guessed she'd be mistaken for Amelia and kidnapped by Mr. Ben Wolfe's henchmen!

Ben's intentions were honorable. He did at least intend to marry Amelia. But his real aim was revenge upon Darlington's family.

Kidnapping the wrong woman upset all his plans, but as Ben got to know the forthright Susanna, he couldn't really admit to being sorry...