Changing Custom Fields on existing catalog items affecting open tickets.

I have noticed that if I make a change to an existing service catalog item the change is reflected in all open, resolved, closed tickets as well.

I have a form that I created that I am asking for Client Name and Email.

Originally I created 2 custom fields for this "Client Name" & "Client Email"

I've sense decided to combine them into 1 new field "Client Name & Email"

When I removed the original 2 fields they were removed from ALL Open, Closed, Resolved tickets.

If I hide the using logic they are hidden form ALL Open, Closed, Resolved tickets.

Two Thoughts

Is this by design or is there a flaw somewhere?

I might need to start just duplicating my request forms, version control.