Swæfberht

Swæfberht was a King of Kent, reigning jointly with Oswine, and possibly also Swæfheard.

Swæfberht issued an undated charter that was witnessed by Oswine [1], and is probably the Gabertus who witnessed a charter issued by Oswine in July 689 [2]. He is usually combined with Swæfheard because of their similar names and overlapping dates, but multiple kingship was commonplace in Anglo-Saxon England, especially in Essex, where Swæfheard originated.

...
Wikipedia