You are able to add duplicate entry in the Buying Team.
Reproducing the Issue
- Go to the Sales work center.
- Go to the Opportunities view.
- Go to the Buying Team tab.
- You can add same member twice as Decision Maker.
There might be some use cases where duplicate entry is required for the Buying Team.
If this requirement is important for you then please consider to implement custom solution using PDI.
KBA , LOD-CRM , Cloud for Customer , How To