Multiple Contact Selectors
In this blog post, Scott Heim talked about adding a Contact Selector Control into your infopath form. Contact Selector Control requires a fix data structure for it to work. My first thought was, this would limit the usage, since you can't have the same field name in a InfoPath form. But wait... I remember OOTB workflow initating forms which is powered by InfoPath Forms Services (at least I was told) does have multiple Contact Selector Controls. Google doesn't help, trying various ways doesn't help... until I clicked on Add Reference, which recreates the entire structure in another section of the form.
Checked Microsoft's documentation. It says
[Quote Url=http://office.microsoft.com/en-us/infopath/HP010967521033.aspx]
The fields and groups that you add to the data source define the type and structure of the data that users can enter into your form. If you want to match the properties of an existing field or group to a new field or group, you can also add a reference field or reference group to your form
......
When you reference an existing field, Microsoft Office InfoPath 2003 creates a new field whose properties are linked and matched to the properties of the original field, including the name and data type. Both fields become reference fields, and any changes you make to one field updates the other field automatically
[/Quote]
I don't understand what they are saying. What worried me was the last statement "changes you make to one field updates the other field automatically". Nevertheless, I still gave the reference field a try, crossing my fingers that I store different information in the two fields. After some testing, I realise what the statement meant. It updates the definition, not the value of the fields, hence you can have different values... 
So how do you add multiple contact selectors?
Using a email form, first of all, follow the instructions in the blog entry to create the structure requried by Contact Selector Control. For myself, I created it under the group named "To"
Then, create a group named "CC"
Right click on the group named Person, and select "Reference"
Select CC, or other target group you want the structure to be in
And your data source should look like this.
Drag and drop the two groups onto the form, and select Contact Selector, and now you have two contact selectors which can have different values!
P.S. Screenshots are done using SnagIt. Saved me lots of time. :)