The left one is Shakespeare’s Portrait in the First Folio (1623). The right one is a mirrored image in the Poems published by John Benson (?-1667).
Ben Jonson wrote the preface of the First Folio. His name is spelt as Ben Johnson in his epitaph (O Rare Ben Johnson). Ben Johnson is a perfect anagram of John Benson.
The portrait in the First Folio is done by Martin Droeshout. His full name appeared only once here among all his works. Mary Sidney is a one-way anagram of Martin Droeshout. With the letter B, her full name Mary Sidney Herbert can be spelt from Martin Droeshout.
The missing B is hidden in Shakespeare’s collar. Note the two lines under his chin, which shapes the collar to letter B instead of D. The page-collar tells the world that William Shakespeare is a page, servant of the Herberts.
Collar has the definition of a band round the neck of a dog as a means of control, identification or ornament.