Opportunity Name default value

Hello everyone,

Our users create opportunities from the company detail page, and each company can have multiple opportunities linked to it.

For Opportunity records the duplicate checking is Opp. Name and Company name fields (along with Contact Id which we are not using)

I need to default the Oppty. Name field to the Company name (and make the field Read-Only at the layout level). Since there is duplicate checking it will throw an error when I try to create a second Oppty. for the same company.

As a workaround I appended the Date to the Company name in the Oppty name field, but there is a slight issue: