From Chaucer’s Second Nun’s Tale, line 328:
The goost that fro the fader gan procede Hath souled hem.
The double-e spelling can be found in the version of Lydgate’s Fall of Princes found in Bodleian MS 263:
Remembryng stories of antiquite, Afforn prouidyng that tresoun nat proceede, Beth ay most dreedful in prosperite.
I can’t find a date for this manuscript, but it’s probably late fifteenth century. (It seems the Bodleian’s web site is even more incomprehensible than that of the U of Toronto library system, and I didn’t think that possible. I can’t find an online catalog description of the manuscript, which would include the date it was copied.)
My guess would be the double-e is there to represent the long vowel, but I can’t say for sure without delving into the early manuscripts, the dialects they were written in, etc.