is it not the same in asian languages? At least some of the asian languages i looked at have a very similar rule. example vietnamese>

toi da giup lam dep:
i (past tense conversion word) help(ed) making slippers
toi da lam anh ay(him/he) an(eat) mi an lien(instant noodles)
i made him eat instant noodles

i used the conversion word da only once in the sentence.
i think in Chinese the conversion word would come after the verb, but i would expect khmer grammar to be similar to Vietnamese?