if you can trouble with duplicate suppliers contact with different invoice, you can change invoice get one suppliers or same people
And Report with different name suppliers will be merge by suppliers same name
1. Check your contact suppliers if you have two data suppliers with same name suppliers
"contacts - suppliers"
2. And for setting merge suppliers - "Tools - Merge suppliers"
Input your name data old suppliers with new name data suppliers "get rid of duplicate name suppliers" then press button Process
3. Done you can get rid of duplicate name suppliers , invoice