Yes you need to uninstall VMware Tools to install Open VMware Tools however I would not do as suggested by JSen for the following reasons. Using Open VMware Tools in this case while it would allow the VMware Shared Folders feature to work you'd need to manually mount the HGFS Share every time you reboot/shutdown and restart the VM, also Copy and Paste as well as Drag and Drop will not work.
As a better workaround, where all will work normally, you can do as I did in Re: VMtools installation problem on Ubuntu 13.04, although if you can wait a few I'm in the process of creating specific patches and the directions how to apply them so as not to use the ones that are a version behind. I should be posting it later today.