Possibility \#2

Possibility #2

When a word or particle ends in a long vowel,

the vowel can be shortened

and the following consonant reduplicated.

ā + khāta > akkhāta

In Kaccāyana this is called (28) para-dvebhāvo ṭhāne

and (26) rassaṃ.

long vowel + consonant

ā	kosa	akkosa	m. insult
ā	khāyati	akkhāyati	pr. is said to be
sammā	gata	sammaggata	adj. gone correctly
ā	ñāya	aññāya	ger. understanding
ā	tharati	attharati	pr. spreads out
mahā	phala	mahapphala	adj. of great benefit
mahā	bala	mahabbala	adj. very powerful
ā	līyati	allīyati	pr. sticks, clings
ā	sasati	assasati	pr. inhales, breathes in

Counter-examples:

avijjā + khanda > avijjākkhandha

su + ā + khāta > svākkhāta

taṇhā + khaya > taṇhākkhaya