Isn't it a custom the couple to be, make different lists of the presents they would like to have? Like what sort of dinner- service, crystal, linen etc etc. The lists are displayed in the special shops (definitely no Ikea) and guests can make a choice to their liking and budget. The presents will be delivered before the wedding and displayed.
This way the newly weds won't get the same present twice and in case of chrystal or porcelain exact the design as requested.
I've read somewhere this was the case when Prince Willem-Alexander married Princess Maxima. I think those lists were ment for their closest friends and other not royals invited to attend the wedding, think of members of the government, celebs etc. I guess the invited Royal houses would send something like a painting, silver, maybe jewels.
I don't know how such things were organised in the old days, it would be likely the same. I also think the foreingn Royals houses would send gifts that represent their country.
Btw. I don't think this thread belongs in the Having Fun section.
Anna