The username of the person who last modified a page is displayed in the properties view of the modified page.

!|script|
|save page|PageOne|by user|Aladdin|
|it's last modified by should be|Aladdin|
|save page|PageTwo|by user|Genie|
|it's last modified by should be|Genie|
|save page|PageThree|
|it's last modified by should be|null|