According to many authorities, to make HaTov VehaMetiv (Who is good and does good) on a second new bottle of wine, that wine must not have been present when they initially said Borei Pri HaGafen (Creator of the fruit of the vine). You are making the Beracha (blessing) of HaTov VehaMetiv on wine that is being brought to the table brand new, and on the excitement of having presented a new bottle of wine.
However, Shulchan Aruch does not rule that way. Shulchan Aruch says that even if both wines are on the table at the same time, they can make the Beracha of HaTov VehaMetiv as long as they open them one after the other in succession—not together and drinking from them simultaneously. They drink from one wine, and then open a second wine. Even if the second wine is on the table in front of them, they can make the Beracha of HaTov VehaMetiv.
Hacham David writes that ideally, one should try to leave the other bottle on the side, not in front of them at the time. But even if they did, they could still make the Beracha of HaTov VehaMetiv, knowing that they are going from one wine to the other, and that the other wine is also a good wine. However, if they already completed the first wine, if let's say they finished drinking the entire bottle of the first wine, then they cannot make, on the second bottle. When the second bottle is brought or opened after the first, some of the first wine must still be there in order to make the Beracha of HaTov VehaMetiv. Have a great day.