These things are tricky because not recognising what is a valid marriage in the country of origin may have far-reaching consequences. For example, it's not OK to tell some guy arriving in a European country who legally has two wives that he needs to choose which of them is the real wife, or even to divorce one of them at home if he seeks political asylum. This might condemn the other wife to a life in disgrace and poverty. (Note: According to what I was taught in religious education, the plight of divorced wives is precisely why Jesus declared divorces illegal - to protect wives against being divorced against their will. Therefore recognising polygamy may be seen as a corollary of European Christian values.)
Or let's say husband and wife are brother and sister, and they are immigrating along with a dozen children of their own (hopefully healthy). It seems clear it would be morally wrong not to recognise this marriage, and it probably would be recognised everywhere in Europe. Maybe even without the children. Even though the two wouldn't be allowed to marry.
In countries where young children can be married, it is not necessarily the case that the spouses are expected, or even allowed, to have sex. This makes the idea of recognising such marriages slightly less revolting, as they are really not much more than arranged marriages that are arranged long in advance. This robs the children of an essential liberty, but I guess it also gives them a sense of security in puberty that is otherwise almost impossible to achieve.
Article 10:31 of the law cited in DavePhD's answer provides:
- A marriage that is contracted outside the Netherlands and that is valid under the law of the State where it took place or that has become valid afterwards according to the law of that State, is recognised in the Netherlands as a valid marriage.
- A marriage is presumed to be valid if a marriage certificate has been issued by a competent authority.
But now what if a toddler married to a bicycle enters the country? Or, somewhat more likely, an 80-year-old Arabic man and his 15-year-old Indonesian wife. The two having married, reluctantly on both sides, to escape draconinan punishment under Shariah law after he raped her.
In the last two cases, Article 10:32 comes to the rescue:
Irrespective of what is provided for in Article 10:31, a marriage that is contracted outside the Netherlands shall not be recognised in the Netherlands where such recognition obviously would be incompatible with Dutch public order.
Note that 'incompatible with Dutch public order' goes far beyond 'that's not how we do things here'. "Public order" is not a good translation, since what is really meant is the term ordre public from international private law, or in English public policy. Moreover, the incompatibility even has to be obvious. Therefore it's not a priori clear (without precedents) whether, based on this law, an official would get away with not recognising a marriage because both spouses are only 12 years old, because they are brother and sister, or because they are actually three spouses. I guess clear cases would be an extreme age gap with one spouse very young, one spouse being a parent of the other, or a large number of spouses.
It may be hard to get information on how these things are handled in practice. Relevant cases are rare and (I guess) often not comparable to each other. They also concern very private matters.
DavePhD's answer concentrated on parts of the law that are actually about contracting marriages in the Netherlands, i.e. about marrying in the Netherlands. I think it's worth explaining why Article 10:29 contains a public order exception for that like Article 10:32 does for recognising marriages, when presumably Dutch public order is already built into Dutch laws.
According to international private law, for things such as marrying, divorcing or changing your name, it is not necessarily the law of the country where you do it that is applied. If everyone involved has the nationality of the same foreign country and nobody involved has the local nationality, then at least to some extent the foreign laws can or must be applied by the local institutions. However, they will only do so to the extent that doing so is not against public order. (The Hague Marriage Convention implemented by the Dutch law cited above and below deals with this. Note that only the Netherlands, Luxembourg and Australia ratified the convention. Wikipedia speculates that this is because the principles in the convention are largely treated for granted anyway.)
E.g., in Germany a divorce can be initiated by either spouse when a marriage has failed. In Turkey they ask whose fault it is and only permit the 'innocent' spouse to initiate the divorce. Since German laws were not too different in this respect until only a few decades ago, this is clearly not against German public order. Therefore, when a Turkish couple who married in Turkey want to divorce in Germany, the German court will apply this law. The German court will also have to deal with complications such as whether the bride must return the nuptial money (which can be a large sum and can amount to brides being sold in a literal sense) - based on Turkish law but taking German public order into account.
Now it should be clear what Article 10:29 does. Suppose, for example, that two citizens of different Sharia law countries live in the Netherlands and want to marry there. By Article 10:28 they can do so if 1. they both satisfy the Dutch conditions, or 2. they both satisfy the Sharia conditions. Article 10:29 sets up some exceptions for the second case. First there is the general provision in Article 10:6:
Foreign law shall not be applied to the extent that the application thereof is obviously incompatible with public order.
And second, just in case of doubt whether any one of them falls under 'obviously incompatible with public order' or not, the exceptions listed in Article 11 of the Hague convention also explicitly prevent a marriage from being contracted in the Netherlands.
Article 11 of the convention actually permits the Netherlands to refuse recognition of a marriage under any of the circumstances listed there. (It doesn't mention contraction.) The fact that they explicitly implemented these exceptions for the contraction of marriages but not for their recognition seems to indicate that they really wanted leeway to sometimes recognise even this kind of marriage. This makes sense, as it allows Dutch authorities to recognise the marriage of a pregnant 14-year old who is in love with her 16-year-old husband and father of the child, as not obviously against Dutch public order.