Deacon El,
I agree with the recollection that Kolya has offered. Tales of cenocephali or dog-headed men were rampant in virtually all cultures and written of, even in Christian texts, as late as medieval times. Iconography depicting such is known and though I'm unaware of it ever being formally condemned, it certainly came to be considered unacceptable.
I doubt that the individuals in the Coptic icon were, in fact, intended to be Saints, unless the purpose was to depict them prior to their conversion. Cenocephaly was generally associated with those deemed to be 'barbarians' - pretty much anyone not of your nation, culture, faith.
In Egypt, given that dog masks honoring Anubis the jackal were worn by priests in conjunction with a number of pre-Christian ceremonials, it seems to me that it would be a natural to so depict those not yet Christianized. The flowering pear tree, toward which the two were peering could as easily be symbolic of Christianity - the pear tree and its fruit has a long history in that regard (a whole array of Renaissance art bears the title 'Madonna of the Pear', depicting Theotokos and Child with one nearby or in hand).
Many years,
Neil
