What does a ROLE CONFLICT mean?

[kangarooPete]

I receive the following errors.  

Received STUN binding error: class=4 number=87 reason='ROLE CONFLICT' from 192.168.1.73:36720

Sending STUN binding error: reason=ROLE CONFLICT

What does this mean?

[Mamadou]

When ICE connection is being negotiated one peer acts as CONTROLLER
and the other as CONTROLLED. It's up to the CONTROLLER to decide which
ICE candidates are the good ones.
By default, the caller is the CONTROLLER.
In some cases (e.g. SIP reINVITE glare), the two peers use the same
role and this is a conflict. The conflict is resolved by comparing the
PRIORITY value in the STUN binding requests.

[kangarooPete]

So in what cases do I 'AddIceCandidate' when OnIceMessage is invoked?  And how do I decide?  A little confused.  Your help is appreciated...