But let me clarify something important: legally, your employer is obligated to give you a copy of the contract signed by both parties. This isn't optional or up to their discretion. Now, the question is how to go about it without creating unnecessary tension, because two months of delay is genuinely a long time.
The safest way is to make a formal written request - preferably by email so you have a record - where you simply ask for the signed copy of the contract. It doesn't need to be aggressive, like "you're legally obligated," but it should be clear and specific: "I'm requesting a copy of my signed employment contract, as agreed." If they keep delaying or refuse, then you have grounds to escalate this with ACT (Autoridade para as Condições do Trabalho) or seek guidance from a worker advocacy organization. But in most cases, a simple email does the trick - sometimes people just forget or don't think it's urgent.
One thing: I'd take the opportunity to check if there's at least something signed by you. Sometimes there are enrollment documents or delivery receipts that prove the employment relationship, even if the formal contract is delayed. Still, push for the complete copy.