Steps:
Person A and B are part of the same organization. Person A and B are using Webmail Calendar. Person A and B do not have create/write permissions on eachother's calendars. Person A creates an event called "Another Thing" on their calendar. Person A invites Person B. Person B accepts the invitation. Person B moves the event to the following day on their calendar.
Observed result:
Email received by Person B: You've been invited to "Another Thing" Email received by host: "Another Thing" has been accepted by Person B Email received by host: "Another Thing" has been updated On Person A's calendar, the event is on the initial day. On Person B's calendar, the event is on the following day.
Expected result:
When user B moves his copy of the event no iTips should be sent.