origin of Latin "do, dare"

[petegray]

> Latin `do, dare' ..and ..PIE {dheH1}

It was strongly argued on this list a few years back that credo was a
compound of *dheh1, not of *deh3.  There is no reason why other compounds
could not also be found in Latin.

How -if at all - would compounds of *dheh1 differ in Latin from the outcome
of compounds  of *deh3?  The initial cluster, being now medial, would appear
as /d/, the reduplication in the perfect would be identical as -didi, the
stem vowel in zero grade  forms would be identically /a/ or after reduction
/i/ (or /e/ before /r/).

What would happen in the present singular?

Peter