This is a potential source of ambiguity, and although the sentence you have sounds rather odd, there are ways of removing all ambiguity.
To answer the first part of your question, yes, "Mike pasa a Violet a Victoria" is an accurate, if ambiguous translation.
However, "Mike la pasa a Violet a Victoria" is not, because the direct object pronoun cannot generally coappear with an post-verbal explicit object pronoun. This is different from the indirect object pronouns that are generally quite commonly included redundantly ("Mike le pasa a Violet a Victoria"), but that still doesn't make our sentence unambiguous.
Because we have a name, we are not able to take advantage of the rule that lets us drop the a personal for animate objects and must introduce both Violet and Victoria with it. That said, there is still another trick we can use to remove the ambiguity. If an explicit direct or indirect object appears pre-verbally, there must be a corresponding (and redundant) object pronoun:
A Victoria le pasa a Violet.
A Violet la pasa a Victoria.
In both of these cases, we know for a fact who is the indirect and the direct object (n.b.: that still doesn't make them sound good). Because Victoria is positioned before the verb, we must include the object pronoun we associate with her. In the first sentence, by including le we know that she must thus be the indirect object pronoun and Violet ends up being the direct. In the second, the opposite happens: because we have la we know that Violet must be the direct object and Victoria the indirect.
Other strategies you can use, if you absolutely must name both people, and depending on the exact verb, could include substituting the preposition a with para for the indirect object (for example, Mike pasa a Violet para Victoria). This technically means there isn't an indirect object anymore, but that's more of a pedantic distinction. Some verbs this sounds better with than others. You could also use the direct object's proper name as an appositive for some other descriptive noun, such as "Mike pasa su amiga, Violet, a Victoria" which enables the deletion of the a personal.
As you can see, in general, it's best to avoid these situations. The only time they really come up is, as in Gustavson's sentences, the verb presentar where ultimately it doesn't make a huge difference anyways who's being introduced to whom.
To answer your last question, in the sentence "Mike la pasa a Violet", Violet is definitively the indirect object, because we have a direct object pronoun that cannot coappear with an explicit direct object after the verb. Thus the only interpretation is that Mike passed something/someone (the la) to Violet.