[Spellyans] Goat

[Michael Everson]

Dan's dictionary has:
gaver, pl gever, gyffres

Nance gives:
gavar, pl gever, gyfras

Nicholas gives:
gavar, pl. gyfras

Gendall gives:
gavar, pl. gever, geffraz

Why is Dan following George's gaver pl gever (with -ar in the sing.)?  
And what is the explanation for "gyffres" given "gifras" and  
"geffraz"? (Certainly there is no need for two f's.)

Michael Everson * http://www.evertype.com/