CV metathesis Q

I've been playing with a sketch where most of the verbs have two basic
stems, CVCVC and CVCCV, to which a number of affixes are added. Mostly,
I've been working on filling in the specific morphology and on subsequent
development (sound changes etc.) but recently, I started wondering exactly
how the two stems came about in the first place. Any ideas?

I should probably mention that the first stem can take (C)V(C) suffixes while
the second can take C((C)V) suffixes and that some of the suffixes also have
alternating forms (CVC vs. CCV and VC vs. CV).

I've been googling and it seems most morphology theorists disapprove of this
sort of thing.

Replies