How can I have the same company as a vendor and customer?

Yes but the name has to be changed slightly, I use a period in the customer name

Welcome to the Community, @mohit1.

You can enter the same company as a Vendor and Customer, and the only way this can be done is if you don't put any first or last name. If you do, one must be abbreviated, and one must be spelled out. Here are screenshots showing an example.

You can see that the Customers name and Vendor name are slightly different. The name is the only error that will pop up if you make it similar, but that's all there is to it. Thank you for coming to the Community and know we're always here helping customers like you with their QuickBooks questions. Happy Monday!

this is the dumbest fix. CHange the spelling? LOL

QBO has some of the most dumbest solutions for users' problems.  Sometimes it's very embarrassing admitting to our customers/vendors that my company is using Quickbooks.