Token mapping minutiae

In token mapping, what’s the correct behaviour if a rule with one or more inputs can be applied in more than one way? For example, with the ERG’s two_one_tmt, if I1 matches a single edge and I2 could match two edges, then is the rule applied once or twice? If the former, which I2 edge is removed? If the latter, I1 is already gone when the rule is applied for the second time, which seems odd.

A similar situation arises for a rule with I1 and C1, where having matched I1 we find that C1 matches multiple edges; if C1’s feature structure contributes to the output then it matters whether we apply the rule once for each match, or only once in total - in which case which edge should we select for C1’s match?

Thanks for any clarification!