Hi Wayne,
From my experience, this usually happens when the profile has more than one linked or subscribed account.
You can follow the steps below to verify this more clearly:
Go to https://techcommunity.microsoft.com
Step 1: Click your profile picture, choose My Settings > Personal Information to check the email address associated with your account and note it.
Step 2: Under Your Info > Manage how you sign in to Microsoft (under Account info) > Account aliases to ensure only one account is connected.
Step 3: Under My Settings > Subscriptions & Notifications > Notification Settings, review the option “Automatically subscribe me to topics I participate in" to see if it’s enabled under multiple accounts or categories, you may receive duplicate emails.
Hope this helps!