There are many cases reported with the complaint of Getting duplicate products showing up in search result and cart. The cause of this issue is due to improper syncing of your inventory with Apptuse.
To resolve this issue, kindly perform do the Manual Sync.
Manual Sync :
Here you can sync your web store manually any time by clicking "Sync the Store" button available on the Apptuse project list page.
To more about Syncing Process CLICK HERE