Ge-twífyldan

According to the Old English Dictionary:

-twýfyldan

ge-twífyldan

to double :-- Seó eahteoðe præteritum getwýfylt ðæt æftre stæfgefég the eighth preterite doubles the second syllable, Ælfc. Gr. 28, 8; Som. 33, 1. Hí beóþ getwyfylde they are doubled, Homl. Th. ii. 372, 35. ge-twifyldan