Can I please have two of those hats I just looked at and one of these?
I'll take two of those XX from before and one of these.
この場合、次のような言い方ができますよ。
ーCan I please have two of those hats I just looked at and one of these?
「さっき見てた帽子２つと、これ１つもらえますか？」
ーI'll take two of those XX from before and one of these.
「さっきのXXを２つと、これ１つください」
ご参考まで！
Then, please give me those two and this one as well.
Then I'd like those two and this one here.
ご質問ありがとうございます。
① "Then, please give me those two and this one as well."＝「それでは、さっきの２つとこの1つも下さい。」
② "Then I'd like those two and this one here."＝「それでは、その２つとこの１つを欲しいです。」
☆「先程」をどちらの文章も"those"と訳しましたが、"those we were talking about"＝「今話していたのを」という言い方も考えられます。
ご参考に。
カナダ 
アメリカ合衆国 
