Hello, Nuzhat.
Welcome to Microsoft's Community. We are more than happy to assist you.
As we understand, you have approved your Exam AL-900 but it has a different MCID.
We are glad to assist you, we will merge your accounts to keep all your titles into your current credentials.
To give you better assistance, we have opened a Private Message as we will request information related to your account. Please look at the right side of the page and click on the icon seen in the image below:
We are attentive for your reply. In case we do not receive a response, the thread will be closed and locked after two business days.
Sincerely,