If you installed PyDev, you really need to remove it in order to get Aptana Studio 3 (which already contains the version of PyDev) - go to help> about> installation details, click on the PyDev plugin and select "remove" (below).
In addition, instead of doing โcheck for updated,โ I recommend that you help> install new software, cancel โcontact all update sites to find the software you need,โ and then log in to the Aptana Studio 3 Update website (as the new version will be there, it will continue and will only update Aptana Studio 3 at this moment).
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