Apple Mail Rule Script help

Hi!
Please help me with an apple script to do the following in Mail and Rules.
A Mac Big Sur Mail which COPIES a mail to another folder but upon copying, mark the copied mail as read whilst leaving the original in its mailbox as unread? How can I do that?

Point is, I have a work mail which’s copy I need to keep under my private mails:
So the work mail is in folder A of the incoming inbox.
When it arrives, I have configured a copy to be automatically copied to mailbox B under my private email. Everything works well.

Now, under the Mac Mail rule, I have additionally selected the copied mail to be marked as unread. This does not work. It marks both the A and the B as unread.

Now I need a script which does the following:
Upon copying the newly arriving mail to B, mark the B as read leaving the A still as unread.

Please help.
Thanks for a swift response.
Thanks