In the top-right corner of your chart, click → Save as copy. In the window that opens, enter a name for the new chart and click Save.
At the top of the chart, click → Duplicate. In the window that opens, enter a name for the new chart and click Apply.
Go to the page of the workbook the chart is in. In the row with the chart, click → Duplicate. In the window that opens, enter a name for the new chart and click Apply.
You can also create a draft of the chart by clicking → Save as draft in the top-right corner of the chart. For more information, see Versioning in DataLens On-premises.