When you copy a task, the following information about it will be copied: task name, duration, work, cost, start and finish dates, constraints, task calendar, task mode, task type, assigned resources, %complete, %work complete, notes, actual duration, remaining duration, actual cost, remaining cost, actual work, remaining work, baseline start, baseline finish, baseline work, hyperlink, address and subaddress.There are more possibilities to copy a task:

1. Click Copy option from Task tab.
2. Press CTRL+C / Command+C
3. Select Copy Task from contextual menu after you right click on a task.

In order to paste a task, select the rows where you want to paste the selection and click Paste.