Why does this patient have a ‘double tongue’?

Poor dental hygiene led to this rare, potentially life-threatening, swelling
Double tongue

This man’s poor dental hygiene came back to bite when he developed such severe cellulitis on the floor of his mouth that it looked like a second tongue.

The 68-year-old presented to a Malaysian ED with a two-day history of neck swelling. A week earlier, he had experienced toothache, followed by fever and difficulty swallowing.