You could always set a new property of your object, as in:
data.temp1 = data.temp
You might or might not want to call delete data.temp. You also might need to clone data.temp, if it’s an object itself.
Note that answers to Javascript questions like this can typically be found very easily by searching StackOverflow. I’m sure the same comment applies to your other question as well, though I’m not a user of ThreeJS. Whether you’re posting here, there or just about anywhere, these days, it will help to familiarize yourself with Markdown to communicate effectively with code, links etc.