I'm not sure whether there is any special aspect of radgrid which offers this.
With a regular wpf datagrid I would consider using a template column and show the two fields in one column.
You then have no problem with the header but of course the template might be a bit fiddly.
The editing template will have two textboxes and the default two textblocks.
Put those in a grid with two columns and use shared size scope so they all line up neatly.
You need to set
Grid.IsSharedSizeScope="True"
On a parent container - I think that'd be the column.
And you need a group on either column of your grid you're putting the data in.
<ColumnDefinition Width="Auto" SharedSizeGroup="A"/>
That then tells all those coliums your datagrid templatecolumn to size to the biggest allowed.
