How did the two site mirrors affect search?

Question

Search Engine Optimization

Hello. I started a new project with a new domain. Everything went well, literally in a month for a fresh domain, Google gave out 500 hits from the search.
The problem is that I have a very old working domain, I store the git repository of the original site on it, with the database connected to the original site. It turns out a direct copy. On this domain, I make changes, test them, and then upload them to git and update them on the main domain.
And the thing is that Google has long known and indexed this old domain. I realized that almost all searches come from the working domain, and the new domain was slowly knocked out of the search (I removed pages from indexing, leaving about 10 out of 30k of them there).
First of all, in the test domain, I created robots.txt with a ban on indexing, and for all addresses I made a 301 redirect to the same address, but on the main domain.
Did you do it right? Will Google bring back the main site in search?