Right: the Reader pattern formula is: Last MSI + latest quarterly + latest out of cycle patch)
It is NOT: Last MSI + previous quarterly + latest quarterly + latest out of cycle patch
Mixing MUI with non-MUI installers is not supported either.
Here's the FAQ text from the link I sent above:
Why do I see a “another version is already installed” error?
Verify no previous product has been installed. If it has, uninstall it. If you’ve already uninstalled, try Microsoft’s or Adobe’s cleaner tool.
This error can also appear if you are patching an AIP in an unsupported order.