If you have duplicate/outdated lead profiles, you can easily merge them profiles on your admin dashboard.
Navigate to the People main menu on the left side of the screen and head over to the Leads page.
Select the lead profile that you'd like to merge by clicking on the 3 dot button on the right side and then select Merge.
On the pop-up, select the duplicate profile by clicking on the + icon inside the Select duplicate box.
Type the duplicate profile's name and select the same. Additionally, you can click on any of the two boxes in the pop-up to make it the primary profile.
Lastly, select the check box on the down left corner of the pop-up to confirm the lead merge and click the Save button.
(The duplicate lead profile will be deleted upon merging and their data will be transferred to the primary account)