Initialize your array as 2D.
CF doesn't really have the concept of multi-dimensional arrays like other languages might, it just effects the same result by allowing any given array element to be, itself, an array.
So there's no trick to doing what you want: just prepend your second array to the first one.
That said, a 2-D array is seldom the best data structure for most requirements. What is the nature of your data? Are you sure you'd not be better off with an array of structs, or possibly having a struct with an element that is an array?
I would agree with Adam regarding the structures. However, if you need to go down the array route, you're looking for syntax like this:
<cfset arrTwo = ArrayNew(1)>
<cfset arrTwo = "Fruit">
<cfset arrTwo = "Meat">
<cfset arrOne = ArrayNew(2)>
<cfset arrOne = "John">
<cfset arrOne = arrTwo>