Can you try deactivating both plugins – The Events Calendar as well as Events Calendar PRO, then double check that both are showing as version 2.0.9 on the plugin admin page – then try activating one more time.
If that doesn’t work it may be worth downloading fresh copies of both plugins, deleting the existing ones and then uploading the new ones using an FTP client (just in case for any reason files from the old versions are still in place).
Please do take the time to back everything up first of all!