That's true, but that's not quite the same as eg: single household median income vs median of all household incomes.
Let's say 90% of men in the US and Norway worked full-time and 80% of women in Norway and 60% in the US worked full-time (or vice-versa) - the various subsets of medians (individual vs families) might not be sensible to compare.
I think most people understand that if you add two people's median income, you'll end up with approx. the double. :)