Just make sure if it's a duplicate, add the duplicate tag on them. For me if I do find a duplicate and it's not tagged as such, I find the best quality one x highest res one and tagged the other as duplicates. Since explicit post are allowed, anything is legal. Just be sure to check the quality of the scan too. Really grainy ones, plus check for the moire effect so we don't get slightly altered colors everywhere. Also, if possible, I would recommend you save them as PNG format, so you have decent quality and you don't get too much jpeg artifacts.