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The average home isn't going to take advantage of the dual gigabit lan with a single computer and one internet provider. No matter how many paths that you create from one device to another, you'll always be limited to the slowest network connection between the two devices.
One way to be able to appreciate bonding dual gigabit connectors is to have a pair of computers with the same network config. This will allow you to copy files between the computers at the maximum speed. However, most people are concerned about downloading content from their internet connection. If you only had a single internet connection, then you're limited to the bandwith by that provider. Furtermore, there's not any ISPs that can match the network speeds of your local lan. So, you'd be limited not only by the speed of your ISP but the entire network path between you and the site of the data.
Another way you can take advantage of the dual network connections is to obtain the services from two ISPs. Then you could connect the seperate connections to each network port. In this configuration you'd be able to have redundancy in case either ISP goes down. If you use a download manager, like DAP for example then you'd be able to take advantage of the aggregate bandwith of both conntections. These file transfer managers are able to do this by downloading segments of a file through both paths.
This process is analogous to taking a pie, cuting the pie into equal segements and feeding it two people. The file is really downloaded twice, once through each path. As each segment is complete then download manager skips that portion of the file from the other path. This effectively allows you to obtain twice the download speed of the file, since it's retreiving two segments of the same file at one time.