DKIM verification failing when using Azure Communication Service as a mail relay

Question

I am relaying emails through Azure Communication Service from my mail server. Both the DKIM for my mail server and Azure ECS are properly verified. However, when I check the email header, two DKIM keys are present - one from my mail server (which fails) and the second from Azure ECS (which passes). I have tested the DKIM on my mail server and it seems to be correct. Can anyone suggest a solution to this issue?

Example email headers:

dkim=pass header.i=@example.com header.s=selector1-azurecomm-prod-net header.b=XWw+Ih2q;

dkim=fail header.i=@example.com.com header.s=s20240604774 header.b=bFJz4PFZ;