There are two ways to copy multiple tasks to another project at a time:

Option 1 Select multiple tasks directly, right click "Copy to new project" ("Progress" and "Date" information not included);

Option 2 Export the tasks and import the .csv file to the new project ("Progress" and "Date" information included)

1. Option 1:
   1. Select "Task";
   2. Drag (or press Ctrl or Shift) to select multiple "tasks";
   3. Right-click "Copy to new project";
   4. Select the project you want to copy them to > "OK".
      
       
2. Option 2:
   1. Slect "Task" > "Export";
   2. Select export property > Click "OK" to export .csv file;
   3. In the new project, select "Task" > "Import" > Select the .csv file from Step 2.2 > "Start import".