Originally Posted by nullfeed
I'm curious, why install google keyboard? Isn't it similar enough, feature wise, to the AOSP keyboard? In fact, aren't they the same? I think the google keyboard is for those stock devices that only have the manufacturers custom keyboard installed. You already have it installed on CM11, maybe that's why you're getting an error.
I don't think aosp and google kb are exactly the same.
plus, if it's showing as an update thru play and the error is coming, then not getting the newest fixes&features.
I would check to see that you don't have some version of it being installed by gapps being used or something. one that is themed maybe or customized will usually contain a different signature than the official one.
also, after you delete it and/or uninstall, reboot device before trying to install thru play.