You match categorical and put intern years under it. Thus, if you apply to 3 places X, Y, and Z, and three intern years, A, B, and C, your rank list would look like this
X-A,B,C
Y-B,A,C
Z-C,A,B
Unless you either don't match at a categorical, or don't match a prelim. You may have to scramble a prelim, but if you rank a prelim year apart from a categorical you have to go to that for a year, and redo the match (or get a spot outside the match).
But it is only one match.