After clicking the duplication box, all inputs that were previously entered disappeared

[bluesky0911]

Describe the bug

1. enter some inputs on the assignee and severity section.
2. Assign the issue as a duplicated issue by clicking the duplication box and selecting one of other issues.
3. Uncheck the duplication box to restore the previously entered inputs (this may be a more natural behaviour on the system from the user's perspective).
4. All prior inputs disappear.

To Reproduce
Steps to reproduce the behavior:

I put it above in my description of the bug.

Expected behavior
A clear and concise description of what you expected to happen.

I also put it above in my description of the bug.

Desktop (please complete the following information):

• OS: [e.g. mac]
• Browser [e.g. safari]
• Version [e.g. 22]

[damithc]

Thanks for raising this @bluesky0911

I tried to reproduce this issue. While severity and bug type seem to remain unaffected, response and assignees are affected by ticking and unticking the duplicate checkbox.
While not critical, it is good if those values can be preserved during the editing phase, in case the user untick the checkbox and wants to continue it as a non-duplicate.