SQL Server 2008 :: Stored Procedure Returning Different Datasets Based On Input Variable

I'm seeing where previous developers have used a single stored procedure for multiple reports, where each report required different columns to be returned. They are structured like this:

CREATE PROCEDURE dbo.GetSomeData (@rptType INT, @customerID INT)
AS
BEGIN
IF @rptType = 1
BEGIN
SELECT LastName, FirstName, MiddleInitial

[Code] ....

As you can see, the output depends on the given report type. I've personally never done this, but that's more because it's the way I learned as opposed to any hard facts to support it.

So what I'm looking for is basically 2-fold.