Assuming you're using the new boards (formerly called the Rapid Board) you could just create two boards looking at the same issues, in one the estimation unit would be Story Points, in the other it would be Original Time Estimate. The burndowns would then work the way you want.
I'm not 100% suere why you'd want to do this though.
I’m a designer on the Jira team. For a long time, I’ve fielded questions from other designers about how they should be using Jira Software with their design team. I’ve also heard feedback from other ...
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