Steam purchased the same game multiple times.
Steam purchased the same game multiple times.
In the cart you can choose "buy as gift." And yes, that implies purchasing it twice—once for yourself and once for your friend.
Unless the game's store page allows purchasing a 2-pack, you'll need to buy each item individually. Edit: If necessary, you can add credit to your Steam Wallet to avoid multiple charges on your card or bank account.
To ensure compatibility, all items must come from the same purchase.