Ahhh, I think I see the problem. Your sources file is 16 months old, and I can see why. On the Wiki page the link for "Download:sources.xml.zip" is the same old one you got. You don't want to use that one. The one now versus the one you dowloaded are a year apart +/- one day, so that may be how that got uploaded by accident.
What version are you running? You should use 8.0.7 on the wiki (even though it says 8.0.6) another thing that could be updated
Anyway, If you have 8.0.7, did you save the original sources.xml when you replaced it with the one from the Wiki? If not you should be able to delete the sources.xml and reinstall 8.0.7 (assuming you are using 8.0.7). It should have the latest sources.xml in it and you don't need the one on the Wiki page.
You should be able to add the Google sources after that.
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