I don't doubt it. However, the source you've chosen (Correio da Manhã) is famously untrustworthy. It's the butt of many jokes here in Portugal, being regarded as everything a news organization shouldn't be.

It was declared on his 'declaration of interests' or whatever it is called. Was also published in Eco and Publico (at least saw in these two).

And from what I remember, a lot of the politicians in the Parliament also have multiple properties, and lets not even remember the 'Rubles' case.