The technical domain is indexed - what to do?

Question

Google

When developing the site, the contractor used the technical domain. Recently it turned out that this technical site is indexed by search engines, visitors go to it. Today the order was even placed. Development has been underway since the beginning of the year, when the technical site began to be indexed - it is not known.
Domains are completely different. Those. the technical domain is not a subdomain of the production domain.
How will search engines react to the fact that a full copy of the technical domain will be posted to our main address?
How is this situation properly handled?

Answer 1

habrahabr.ru/company/webnames/blog/204754
habrahabr.ru/post/168471
s?

Answer 2

Make a redirect to the correct domain.

Answer 3

1. Close the technical domain in robots.txt
2. Put a 301 redirect in .htaccess
3. Add the technical domain to Google Webmaster Tools and then submit a request to remove the domain from the Google index