Hi there, Becky.
Yes, you can set up a customer who is also a supplier in QuickBooks Online (QBO). You may use a distinct character on the Display name as since the system won't accept identical names for a customer, vendor, and employee.
Example:
- Customer: Angel SmithC
- Vendor: Angel SmithV
I've added these screenshots for your visual references.


For additional resources about adding customers or vendors in QBO, you can check out these articles:
Aside from that, you can also get more tips while handling your customer or vendor transactions through these links:
Please let me know how else I can help you with setting up your customer or supplier in QBO. I'm more than happy to provide additional assistance. Keep safe!