Duplicate SSID different MAC addresses

I am sharing an internet connection and am relatively close to the router (linksys) but because of the materials my building is constructed with I get a poor connection. So, there is a closer range extender that I can connect to, the range extender is also a linksys range extender, and I have no problems when I connect to it. The only problem is actually getting connected to it in the first place. My computer will automatically connect to the router rather than the range extender despite the stronger signal from the range extender. They both have the same SSID, and obviously different MAC addresses. Is there a way to force my computer to only connect to the range extender and ignore the signal from the router? Can I select a wireless network to join by MAC address rather than SSID?