Emails are marked 'read', when another recipient marks it as read using a rule

REPRODUCE:
1. Create a rule as User1:

When the message...
    Includes these words in the subject.... 
    (add a word like 'test')
Do the following...
    Mark the message as read...

2. Send an email to User1 and User2

RESULT:
The email is marked as read in User2's inbox (as well as in User1's)

EXPECTED RESULT:
The email should only be marked as read in User1's mailbox