DAB Controller described a separation error when traffic was allowed to land on Runway 7R and Runway 16 simultaneously; the reporter suggesting the existing LAHSO Order be modified to allow this type of operation.

Narrative

A C172 was on a 3 mile final to Runway 16. A DA42 was on a 5 mile final. I had 5 aircraft holding short of Runway 16 awaiting departure. I circled the C172 to Runway 7R to get some departures out; prior to the DA42 landing on Runway 16 and the C172 landing on Runway 7R. After getting a couple departures out; I cleared the C172 to land on Runway 7R and then cleared the DA42 to land on Runway 16. At that time another aircraft had departed and tagged up on the wrong code; I called AR-N to inform them. The C172 was rolling out on Runway 7R and was told to turn left at Whiskey; no response; and was then told to hold short of Runway 16 and he said unable. I turned to see the DA42 progress on the Runway 16 final and saw that it wasn't going to work so I told the DA42 to go around on Runway 16 and the pilot said we just touched down. Recommendation; review LAHSO order with reference to type aircraft that can land and hold short at DAB. I realized after the fact that I had more things I could have done and didn't react in time to send the aircraft around.