How to migrate a gitlab between two LDAP servers?

Hello everyone!

I have a question:
We have a gitlab-ce(ver:13.12.12 On CentOS 7.4) server with some accounts from LDAP (Microsoft Windows Active Directory) and some internal accounts.

Now, due to practical needs, we need to switch gitlab’s from the current Microsoft Windows Active Directory (AD1) to the new Microsoft Windows Active Directory (AD2).
Special note: the account names on AD1 and AD2 are exactly the same.

But when I tested it, I found that I switched from the original AD1 to AD2. After the account logs in to gitlab (using AD2), the account name will automatically add the number 1 in the background (for example: the old account called e-aabbcc is in AD1, but after logging in on the new AD2, the account name becomes e-aabbcc1), and the account is based on the groups and projects created in the original AD1 domain, and the groups and projects previously created by the account have disappeared.
This is not the result I want.

Excuse me, how do I switch from my previous domain to the new Microsoft Windows Active Directory? Is there any complete documentation to study?