[dotancohen]

Now I understand your question. It is possible that because the first and second wife are not registered with the state, the men are "marrying" for the first (official) time. That could even be why this practice is usually done for the third- and forth- wife, and not the first or second. It is possible that these marriage are the "official" state-registered marriage. That's my guess, I don't really know.

[dmix]

I believe it’s relevant because why make a change to law if these polygamists aren’t exploiting the marriage law?

[dotancohen]

My guess would be because it is impossible to enforce any "law" governing how these people lead their everyday lives (who they marry) but it is possible to enforce laws regarding the movement of people across borders.