World's easiest to use A/B, Split and Multivariate testing tool.
great for AB tetsing. Has heatmaps and clickmaps also
The issue happens when the VWO tracking code is added to the page twice. So do make sure that when you are using the plugin, any other instance of the VWO tracking code should be removed from the page. If you still face issues, try switching to the Sync version of code (presented as option inside the plugin).