I can't decide between two schemes for my conlang:

Scheme 1:

lieti = teacher
lieta = to teach [SO]
lietu = pupil ( = student of [SO] )

lieta-kau = to be teached by [SO]


Scheme 2:

lieti = teacher
liete = to teach [SO]
lieto = to be teached by [SO]
lietu = pupil


Could you make some comments to help me decide?

I  prize clarity and brevity, but also avoidance of loss of
information. I have even considered allowing both vowel and consonant
gemination in order to avoid loss of information. For instance, one
could write (and say) "lietoo" to avoid confusion with "liete", but I
fear it is inelegant. BTW, does any natlang have some kind of
"gemination for emphasis"?

Até mais!