Occasionally during the process of getting start on Amazon you might be forced to recreate listings, convert listings to FBA or FBM, or create duplicate offers. Some of these processes result in duplicate FBA inventory on Amazon that SKULabs combines because normally it's a transition to a new FNSKU you're continuing to sell online.
On an item's page you may find this additional inventory....
If you take your SKU, in this case "ANYSKU" and navigate to your Inventory tab, then click the "Warehouses" page you will be able to load your FBA inventory data directly from Amazon after opening up your FBA Warehouse. Search for the SKU you copied before to find all linked FBA inventory for that SKU.
Now how 12 units are available under one FNSKU, while 2 units are available under another. If you believe these products are different products entirely you will want to correct the problem in SKULabs by unlinking the listing and relinking it to another product. You can find the causes for this by speaking with Amazon support. Normally this inventory can be found within SellerCentral.