This behavior is likely to be achieved if you are using random values for your X-Axis and the bar items are overlapping because the X-Axis values are too close.
I've attached a sample where you can see how to create a chart like the one you've described as your expected result.
You can also find more information about how to create charts in our help topics here or checkout some of the demos examples here.
Greetings,
Peshito
the Telerik team
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