I'm fairly confident the coin is old - its an obscure coin worth about £5 - with minimal collectors interested in it. It certainly not a modern fake - though it could be a contemporary one I suppose - but I doubt it. It looks legit.
My apologies in advance if this is completely off-base (I know nothing about the coins of Portugal), but is this simply a coin-alignment vs. medal-alignment issue? If I rotate by 180 degrees one of the two reverses of the coins you show from Numista, they seem very similar besides some differences in the size of the lettering in the legend. I don't know if the size of the lettering is a key indicator of type, however. I note the first coin listed from Numista states it has coin alignment, but for the 2nd one it's not specified whether it is coin or medal alignment.