Copy custom project property values from one env to other???

How to copy custom project property values from one env to other?
for ex: 1. in project view, go to environment tab
2. create one env; example - Dev
3. create custom properties and insert values for those properties.
4. create second env; example - INT
5. select the radio button= copy endpoints and credentials from the project
6. go to the custom properties of newly created env
Here you can see only properties are copied and not there values.
So the question is how to copy the custom project properties from one environment to another?