Welcome to the forums

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Pity on your first question you get two different answers.
I wouldn't really worry about it if I were you.
It will be using the ethernet connection when both are available for the reason I gave to ggremlin. There is only one connection between the router and the internet though, so no real problem.
It would be technically slightly preferable to disable one or the other but I don't think it is important.
If you won't be moving around with the laptop and are happy with it near the router, disable wireless. If you want to have it away from the router then disconnect the ethernet cable as ggremlin says.
You might find when disconnecting the ethernet cable that you have to tell it to re-connect to the wireless side, as I find sometimes it looks as though it is connected but it doesn't automatically start to use it if it was using the ethernet connection.
If you start the computer from scratch though, without the ethernet connection, the wireless should start automatically if you have set it to do so.
Good luck.
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