Everyone who has done PLC programming over Ethernet has inadvertently assigned duplicate IP addresses and felt foolish about it for a few seconds.
If you can, post a screenshot of your FactoryTalk View ME Transfer Utility and how you have browsed and selected the PanelView Plus to which you are downloading the *.MER runtime application file.
Usually, "the destination selected is not a valid FactoryTalk View ME Station destination" means that you have inadvertently selected a PLC or other device in your browse, or the PanelView is a newer firmware revision than is recognized by your software.
The PV+ menus should tell you the firmware revision of your PV+ terminal, and of course the Help -> About on FTView Studio will tell you what version and support you have installed.