This may help - not entirely related, but perhaps useful.
Check the blades are clean.
This will test to see if the torquemeters are reading the same - put one engine at idle, and pull up to light on the skids and note torque on 'good' engine. Then leaving the collective at the same position, bring engine that was at idle to normal position, and reduce formerly 'good' engine to idle. Should have the same torque.
And there are two ways to do hover out of ground effect - 'hover up', or 'fly in'.
'Fly in' is done by transitioning to the hover from forward flight at a height well above the break line from in-ground-effect to out of ground effect (try 150' AGL).
The 'hover up' method starts from IGE and attempts to climb up to OGE.
My experience is that there is probably at least 5-7% difference in power required to hover - with the 'fly in' requiring less power.
I've never been able to determine why there would be difference, but there is.