Is it possible to add two different companies with same name and GSTIN in Swipe?

Yes, it is possible to add two different companies with the same name and GSTIN in Swipe.

Note:
The plan for both companies will be separate. If you want the same plan that you are currently using for your company, you can buy the same plan for the other company.
Also, the data for both companies will be managed separately, including reports, inventory, documents, etc.