What you are seeing is called world wrap. It's kind of like being able to spin the globe. The Bing Maps V8 SDK doesn't have a specific option to disable this feature, however, you can set the maxBounds
option of the map to the limits of a single "world" and it will prevent the ability to pan the map infinitely left and right, however it likely won't change how things are rendered on the map. Here is an example of setting this option when loading the map:
var map = new Microsoft.Maps.Map(document.getElementById('myMap'), {
maxBounds: new Microsoft.Maps.LocationRect(new Microsoft.Maps.Location(0,0), 360, 180)
});