Thought I would share - being as until recently we've been paying for two full price needlessly, not noticing the offer at the bottom of the ticket, doh. Perhaps others are not so unobservant, but here goes. Every full price ticket at Castello Lopes has an offer to return within 2 weeks and, upon showing the offer ticket, you can get two tickets and only pay for one (which will have the same offer on it for next time). You must be buying a full price ticket to get the offer, and you must request one full price ticket when you use the offer, so don't ask for a concession even if you're a youngster or a pensioner, this works out cheaper for a couple. First time round I guess you could buy one full price and one concession. Even works on a Monday when usually full price is 5.80€ instead of 6.50€.
Sorry Algarvians - I think Castello Lopes only have cinemas in Central and North PT.