Acitve Directory network account username change to userid.domain

Hello Expert .

we have few users has reported their user Id changed by itself to userID.Domain should be UserID only , this is only showing in command line example below when they tried to log in to laptop . or if you go to windows explorer C:\users

some user has 2 windows profiles created on c drive .
1- C:\Users\userID
2- C:\Users\userid.MYDOMAIN

causing some application to run properly.

when I go to CMD and type set enter

TEMP=C:\Users\userID~1.MYDOMAIN\AppData\Local\Temp
TMP=C:\Users\USERID~1.MYDOMAIN\AppData\Local\Temp
UATDATA=C:\WINDOWS\CCM\UATData\D9F8C395-CAB8-491d-B8AC-179A1FE1BE77
USERDNSDOMAIN=MYDOMAIN.INTERNAL
USERDOMAIN=MYDOMAIN
USERDOMAIN_ROAMINGPROFILE=MYDOMAIN
USERNAME=USERID
USERPROFILE=C:\Users\USERID.MYDOMAIN
windir=C:\WINDOWS

Could you please assist me to trouble shoot the issue or able to assist my team to find the solution please

we just have been migrated to windows 10 pro and running windows server 2012 .

my knowledge of IT is level 1 , I appreciate your help to step me through the issue

thank you in advance .