Is there a name for the literary device of having multiple speakers alternating in the same paragraph?

In The Voyage of the Dawn Treader, C. S. Lewis has:

. . . Lucy could only say, "It would break your heart." "Why," said I, "was it so sad?" "Sad!! No," said Lucy

and in the Star Trek novel, The Wounded Sky, Diane Duane has (in one of many nods to Narnia -- the whole book is, in many ways, one big homage to Narnia) an almost-verbatim quote, using the same device of two speakers alternating in a single paragraph.

Is there a formal name for this device?

Note that I'm not accusing Diane Duane of plagiarism here: the Narnian nods are too obvious for her not to have intended readers familiar with Narnia to recognize them.

I'm not sure if this applies, but there's a very related term in drama and poetry called stichomythia

A form of verbal sparring used especially in ancient Greek drama or poetry, in which single lines of verse or parts of lines are spoken by alternate speakers.

and here

Dialogue especially of altercation or dispute delivered by two actors in alternating lines (as in classical Greek drama).

It might not be too much of a stretch to use this term to describe a literary device as well.