A glancing point of similarity, this, but given how widely read Landor's Imaginary Conversations were in the nineteenth-century perhaps this passage (from 'Conversation between Chaucer, Boccaccio and Petrarca') was at the back of Carroll's mind when he wrote the Tweedledee and -dum episode. Landor's Chaucer takes up much of this conversation with a lengthy tale about the bumbling, cowardly but endearing English knight Sir Magnus Lucy. Sir Magnus is 'a knight of ample possessions and of no obscure family, in the shire of Warwick.' He yearns to be a warrior, but is too childish.
The good Lady Joan [his Mum] would never let him enter the lists at jousts and tournaments, to which indeed he showed small inclination, nor would she encourage him to practise or learn any martial exercise. He was excused from the wars under the plea that he was subject to epilepsy; somewhat of which fit or another had befallen him in his adolescence, from having eaten too freely of a cold swan, after dinner. To render him justice, he had given once an indication of courage. A farmer's son upon his estate, a few years younger than he had become a good player at quarter-staff, and was invited to Charlecote, the residence of the Lucys, to exhibit his address in this useful and manly sport. The lad was then about sixteen years old, or rather more ; and another of the same parish, and about the same standing, was appointed his antagonist. The sight animated Sir Magnus; who, seeing the game over and both combatants out of breath, called out to Peter Crosby the conqueror, and declared his readiness to engage with him, on these conditions: First, that he should have a helmet on his head with a cushion over it, both of which he sent for ere he made the proposal, and both of which were already brought to him, the one from a buck's horn in the hall, the other from his mother's chair in the parlor; secondly, that his visor should be down; thirdly, that Peter should never aim at his body or arms; fourthly and lastly, for he would not be too particular, that, instead of a cudgel, he should use a bulrush, enwrapped in the under-coat he had taken off.The fight goes ahead, although a wag puts sneezing powder (seriously: 'a powder of a sternutatory quality' Landor calls it) in Sir Magnus's helmet and he collapses crying aloud that he is dying. ('crying, "Oh Jesu! Jesu! I am in the agonies of death: receive my spirit!" John Crosby kicked the ankle of the farmer who sat next him on the turf, and whispered, "He must find it first".') All very ho-ho, no doubt; but also more than a little Tweedledumdeeish, no?