Mantis has a feature to move an issue from one project to another project.
Step 1 − Go to the View Issue Details page that needs to move to another project.
Step 2 − Click Move as shown in the following screenshot.
Step 3 − In the Move Issue page, select the new project where the issue will move and click the Move Issues button as shown in the following screenshot.
Step 1 − Go to the View Issue page.
Step 2 − Set the filter and navigate to the Viewing Issues section where you will find a list of issues.
Step 3 − Check the checkboxes for all issues that are required to be moved.
Step 4 − Select the Move option from the dropdown present at the bottom of the screen and then click OK.
The following screenshots display how to move multiple issues at a time.
Step 5 − In the Move Issues to page, select the new project, where the issue will move and click the Move Issue button as shown in the following screenshot.