@mahram,
Rendering multiple charts in a page seems to be working fine. Please refer to this tutorial for step-to-step instructions on rendering multiple charts in a page.

If you are still facing issue, can you kindly create JSFiddle reproducing the issue you are facing & share it with us so that we can look into the code / chart-options being used, understand the scenario better and help you resolve?
—
Vishwas R
Team CanvasJS